Showing papers on "Metamagnetism published in 2013"
TL;DR: In this paper, the effect of a magnetic field in the linear sigma model has been studied in the context of holographic metamagnetworks. But it is not shown that the effect can be applied to magnetized condensed matter systems.
Abstract: From the Contents: Chiral magnetic spirals.- Magnetized matter in the Sakai-Sugimoto model.- Charge-dependent correlations in heavy ion collisions.- Superconductivity from rho meson condensation in QCD.- Lattice studies of QCD phase transitions in a magnetic field.- Holographic Metamagnetism.- Dense quark matter in a magnetic field.- Effects of a magnetic field in the linear sigma model.- Chiral Magnetic effect II.- Debye screening in magnetic field through holography.- Holographic magnetized fermions.- Chiral magnetic effect in holographic models.- Applications of the AdS/CFT correspondence to magnetized condensed matter systems.
241 citations
TL;DR: In this paper, the infinite class of d = 3 CFTs dual to skew-whiffed AdS 4 × SE 7 solutions of D = 11 supergravity at finite temperature and charge density and in the presence of a magnetic field were analyzed.
Abstract: We analyse the infinite class of d = 3 CFTs dual to skew-whiffed AdS
4 × SE
7 solutions of D = 11 supergravity at finite temperature and charge density and in the presence of a magnetic field. We construct black hole solutions corresponding to the unbroken phase, and at zero temperature some of these become dyonic domain walls of an Einstein-Maxwell-pseudo-scalar theory interpolating between AdS
4 in the UV and new families of dyonic $ Ad{S_2}\times {{\mathbb{R}}^2} $
solutions in the IR. The black holes exhibit both diamagnetic and paramagnetic behaviour. We analyse superfluid and striped instabilities and show that for large enough values of the magnetic field the superfluid instability disappears while the striped instability remains. For larger values of the magnetic field there is also a first-order metamagnetic phase transition and at zero temperature these black hole solutions exhibit hyperscaling violation in the IR with dynamical exponent z = 3/2 and θ = −2.
87 citations
TL;DR: The title heterobridge system exhibits the coexistence of AF ordering, SCM-derived multi-relaxation dynamics, field-induced metamagnetism and field- induced spin-glass-like dynamics.
60 citations
TL;DR: It is demonstrated that the magnetic Grüneisen parameter ΓH indeed both changes sign and diverges as required for quantum criticality, and displays a characteristic scaling behavior but only on the low-field side H≲H(BCP), indicating a pronounced asymmetry with respect to the critical field.
Abstract: Bicritical points, at which two distinct symmetry-broken phases become simultaneously unstable, are typical for spin-flop metamagnetism. Interestingly, the heavy-fermion compound YbAgGe also possesses such a bicritical point (BCP) with a low temperature T(BCP)≈0.3 K at a magnetic field of μH(BCP)≈4.5 T. In its vicinity, YbAgGe exhibits anomalous behavior that we attribute to the influence of a quantum bicritical point that is close in parameter space yet can be reached by tuning T(BCP) further to zero. Using high-resolution measurements of the magnetocaloric effect, we demonstrate that the magnetic Gruneisen parameter ΓH indeed both changes sign and diverges as required for quantum criticality. Moreover, ΓH displays a characteristic scaling behavior but only on the low-field side H≲H(BCP), indicating a pronounced asymmetry with respect to the critical field. We speculate that the small value of T(BCP) is related to the geometric frustration of the Kondo lattice of YbAgGe.
56 citations
TL;DR: In this paper, the authors studied the martensitic transformation of metamagnetic shape memory alloy Ni50Mn34.5In15.5 in the magnetic fields up to 12 T.
Abstract: We study the martensitic transformation (MT) of metamagnetic shape memory alloy Ni50Mn34.5In15.5 in the magnetic fields up to 12 T. The observed dependence of the MT temperature, Tm, on the field is highly nonlinear. As far as magnetization change, ΔM, remains field-independent, a depart from linearity of Tm(H) function is attributed to a decrease of the transformation entropy, ΔS. This decrease correlates with the parameter (TC-Tm), controlled by magnetic field, where TC is the Curie temperature of austenite, and with the dependence of ΔS on the width of the MT temperature interval deduced from a ferroelastic model of MT.
51 citations
TL;DR: In this paper, the magnetic entropy change (ΔS) involving martensitic transition in both conventional and metamagnetic NiMn-based Heusler alloys is reviewed.
Abstract: Our recent progress on magnetic entropy change (ΔS) involving martensitic transition in both conventional and metamagnetic NiMn-based Heusler alloys is reviewed. For the conventional alloys, where both martensite and austenite exhibit ferromagnetic (FM) behavior but show different magnetic anisotropies, a positive ΔS as large as 4.1 Jkg−1 K−1 under a field change of 0–0.9 T was first observed at martensitic transition temperature TM ~ 197 K. Through adjusting the Ni:Mn:Ga ratio to affect valence electron concentration e/a, TM was successfully tuned to room temperature, and a large negative ΔS was observed in a single crystal. The −ΔS attained 18.0 Jkg−1K−1 under a field change of 0–5 T. We also focused on the metamagnetic alloys that show mechanisms different from the conventional ones. It was found that post-annealing in suitable conditions or introducing interstitial H atoms can shift the TM across a wide temperature range while retaining the strong metamagnetic behavior, and hence, retaining large magnetocaloric effect (MCE) and magnetoresistance (MR). The melt-spun technique can disorder atoms and make the ribbons display a B2 structure, but the metamagnetic behavior, as well as the MCE, becomes weak due to the enhanced saturated magnetization of martensites. We also studied the effect of Fe/Co co-doping in Ni45(Co1−xFex)5Mn36.6In13.4 metamagnetic alloys. Introduction of Fe atoms can assist the conversion of the Mn—Mn coupling from antiferromagnetic to ferromagnetic, thus maintaining the strong metamagnetic behavior and large MCE and MR. Furthermore, a small thermal hysteresis but significant magnetic hysteresis was observed around TM in Ni51Mn49−xInx metamagnetic systems, which must be related to different nucleation mechanisms of structural transition under different external perturbations.
37 citations
TL;DR: In this paper, the magnetic properties of the martensitic phase in Ni-Mn-In-Co alloys have been determined, showing the presence of superparamagnetic domains inside a paramagnetic matrix.
Abstract: The magnetic ground state of the martensitic phase in metamagnetic shape memory alloys seems to be dependent on the analyzed system. In Ni2Mn1+xZ1−x (Z = In, Sn, and Sb) alloys, ferromagnetic and antiferromagnetic interactions coexist in the martensitic state. Different mechanisms, i.e., reentrant spin glasses, superparamagnetism, or superspin glasses have been proposed to explain the martensitic magnetic behavior. In this letter, the magnetic properties of the martensitic phase in Ni-Mn-In-Co alloys have been determined. The martensitic phase shows the presence of superparamagnetic domains inside a paramagnetic matrix. On cooling, superspin glass features occur when interacting clusters are frozen below a critical temperature.
32 citations
TL;DR: In this article, it was shown that tricritical metamagnetism can arise in an antiferromagnetic metal due to the dependence of local moment interactions on the magnetisation state.
Abstract: We describe a `disordered local moment' (DLM) first-principles electronic structure theory which demonstrates that tricritical metamagnetism can arise in an antiferromagnetic metal due to the dependence of local moment interactions on the magnetisation state. Itinerant electrons can therefore play a defining role in metamagnetism in the absence of large magnetic anisotropy. Our model is used to accurately predict the temperature dependence of the metamagnetic critical fields in CoMnSi-based alloys, explaining the sensitivity of metamagnetism to Mn-Mn separations and compositional variations found previously. We thus provide a
finite-temperature framework for modelling and predicting new metamagnets of interest in applications such as magnetic cooling.
27 citations
TL;DR: In this article, the martensitic transformation behavior in a Ni45Co5Mn36In14 was investigated at low temperatures and almost perfect superelasticity was confirmed below 200 K.
Abstract: The martensitic transformation behavior in a Ni45Co5Mn36In14 was investigated at low temperatures. Almost perfect superelasticity was confirmed below 200 K. The reverse transformation finishing stress monotonically decreased with decreasing temperature and the forward transformation starting stress changed from a decrease to an increase at ∼125 K. The temperature dependence of equilibrium stress had the same tendency as that of equilibrium magnetic field, allowing the thermal transformation arrest temperature to be determined. The temperature dependence of hysteresis in stress-induced transformation was also similar to that in magnetic-field-induced transformation, and the levels of dissipation energy yielded by the stress and magnetic field were intrinsically equivalent.
26 citations
TL;DR: In this paper, the effect of hydrostatic pressure on the magnetic and magnetocaloric properties of Ni2−XMn1+XGa alloys around the martensitic transformation temperature (TM) has been investigated.
Abstract: The effect of hydrostatic pressure on the magnetic and magnetocaloric properties of Ni2−XMn1+XGa (X = 0, 0.15) Heusler alloys around the martensitic transformation temperature (TM) has been investigated. We find that magnetic field increases and decreases the characteristic transitions temperature for X = 0 and 0.15, respectively, and increases the saturation magnetization of martensite phase for both the alloys. However, the hysteresis width decreases for both the alloys as we increase the magnetic field to 5 T. Application of hydrostatic pressure increases (decreases) the TM for X = 0 and 0.15. Pressure stabilizes the martensite phase with the increase of TM for Ni2MnGa, whereas the austenite phase gets stabilized with the decrease of TM in Ni1.85Mn1.15Ga (x = 0.15). Metamagnetic-like transition is suppressed for both the specimens with increasing pressure. The maximum magnetic entropy change (ΔSM max) is found to reduce from 19.2 J kg−1 K−1 (P = 0) to 6.04 J kg−1 K−1 (P = 9.69 kilobars) around TM for Ni2MnGa and it decreases from 8.9 J kg−1 K−1 (P = 0) to 1.27 J kg−1 K−1 (P = 7.4 kilobars) around TM for Ni1.85Mn1.15Ga.
23 citations
TL;DR: In this article, a four-level relaxation model was proposed for the description of the Mossbauer spectra of ferrimagnetic nanoparticles under conditions of metamagnetism.
Abstract: A four-level relaxation model in the two-sublattice approximation has been proposed and implemented for the description of the Mossbauer spectra of ferrimagnetic nanoparticles under conditions of metamagnetism. This model is a basis for the further development of the theory of magnetic dynamics of ferrimagnetic nanoparticles and allows the qualitative description of the size effects, which for nearly half a century were observed repeatedly in the experimental absorption spectra of 57Fe nuclei in ferrimagnetic nanoparticles.
TL;DR: In this article, the temperature-pressure-magnetic field phase diagram was made from electrical resistivity measurements for the ferromagnetic Kondo lattice CeRuPO, where the ground state at zero field changes from the FM state to another state, which is suggested to be an antiferromagnetic (AFM) state, above 0.7 GPa.
Abstract: We report the temperature-pressure-magnetic field phase diagram made from electrical resistivity measurements for the ferromagnetic (FM) Kondo lattice CeRuPO. The ground state at zero field changes from the FM state to another state, which is suggested to be an antiferromagnetic (AFM) state, above \({\sim}0.7\) GPa, and the magnetically ordered state is completely suppressed at \({\sim}2.8\) GPa. In addition to the collapse of the AFM state under pressure and a magnetic field, a metamagnetic (MM) transition from a paramagnetic state to a polarized paramagnetic state appears. CeRuPO will give us a rich playground for understanding the mechanism of the MM transition under comparable FM and AFM correlations in the Kondo lattice.
TL;DR: In this paper, the authors examined the character of the itinerant magnetic transition of DyCo by different calorimetric methods, thereby separating the heat capacity and latent heat contributions to the entropy.
Abstract: We examine the character of the itinerant magnetic transition of DyCo${}_{2}$ by different calorimetric methods, thereby separating the heat capacity and latent heat contributions to the entropy---allowing direct comparison to other itinerant electron metamagnetic systems. The heat capacity exhibits a large \ensuremath{\lambda}-like peak at the ferrimagnetic ordering phase transition, a signature that is remarkably similar to La(Fe,Si)${}_{13}$, where it is attributed to giant spin fluctuations. Using calorimetric measurements, we also determine the point at which the phase transition ceases to be first order: the critical magnetic field, ${\ensuremath{\mu}}_{0}$${H}_{\mathrm{crit}}$ $=$ 0.4 \ifmmode\pm\else\textpm\fi{} 0.1 T and temperature ${T}_{\mathrm{crit}}$ $=$ 138.5 \ifmmode\pm\else\textpm\fi{} 0.5 K, and we compare these values to those obtained from analysis of magnetization by application of the Shimizu inequality for itinerant electron metamagnetism. Good agreement is found between these independent measurements, thus establishing the phase diagram and critical point with some confidence. In addition, we find that the often-used Banerjee criterion may not be suitable for determination of first order behavior in itinerant magnet systems.
TL;DR: In this article, a DC magnetron sputtering on LaAlO3 and SrTiO3 (STO) substrates was shown to undergo paramagnetic-ferromagnetic (PM-FM) transition at TC ∼116 K and shows insulator-metal transition (IMT) at TIM∼∼ 115 K.
Abstract: Sm0.5Sr0.5MnO3 thin films were deposited by DC magnetron sputtering on LaAlO3 (LAO) and SrTiO3 (STO) substrates. The film on LAO, which is under compressive strain, undergoes paramagnetic–ferromagnetic (PM–FM) transition at TC ∼116 K and shows insulator-metal transition (IMT) at TIM ∼ 115 K. The film on STO is under tensile strain and has TC ∼ 112 K; and shows IMT at TIM ∼ 110 K. Around ∼80 K, the film on STO shows a broad peak in the resistivity that could be seen as the reentrant IMT due to appearance of a metamagnetic state, the presence of which is confirmed by the discontinuous irreversible jumps in the magnetic field dependent isothermal resistivity at T < 85 K. These signatures of the metamagnetic state are not seen in the film on LAO. The occurrence and absence of metamagnetic state in films on STO and LAO, respectively, has been explained in terms of the control of the competing FM metallic and antiferromagnetic–charge ordered insulating (AFM–COI) phases by the different strain states in these films.
TL;DR: Detailed discussions of molecular materials based on the W(V) ion are reviewed, including slow relaxation of magnetization, typical for single-molecule magnets and single-chain magnets, spin-canting, and metamagnetism.
Abstract: Metal ions heavier than the 3d metals have attracted increasing attention due to their strong magnetic exchange coupling, arising from the diffuse nature of the extended valence orbitals of the 4d and 5d elements and the involvement of a large magnetic anisotropy contingent on their strong spin–orbit coupling. [W(CN)6(L)]1−/2− (L = 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen)) serves as a suitable building block for constructing molecule-based magnetic systems. Discrete molecular entities and one-dimensional chains are preferably obtained when the restricted paramagnetic precursor [W(CN)6(bpy)]− encounters metal counterparts with the available coordination sites. The bimetallic magnetic assemblies exhibit a variety of magnetic features, along with a magnetostructural correlation. These include slow relaxation of magnetization, typical for single-molecule magnets and single-chain magnets, spin-canting, and metamagnetism. The two-dimensional structure is stabilized by using the reduced [W(CN)6(bpy)]2− complex. In this perspective article, detailed discussions of molecular materials based on the W(V) ion are reviewed.
TL;DR: The magnetic studies indicate that 1 is a single-chain magnet with two slow magnetization relaxation processes which has for the first time been found in this type of chain complex, while 2 shows a field-induced metamagnetic behavior.
Abstract: Two chain compounds built with anti–anti acetate bridged MnIII3O units, [Mn3O(Clppz)3(EtOH)4(OAc)]n (1) and [Mn3O(Clppz)3(EtOH)2(OAc)]n (2), were synthesized and characterized. The magnetic studies indicate that 1 is a single-chain magnet with two slow magnetization relaxation processes which has for the first time been found in this type of chain complex, while 2 shows a field-induced metamagnetic behavior. The quite different magnetic behaviors resulted from the different number of coordinated ethanol molecules on the MnIII3O unit, four ethanol molecules for 1, and two ethanol molecules for 2. The best fittings to the experimental magnetic susceptibilities gave J1 = −2.72 cm−1, J2 = −4.34 cm−1, zJ = 1.24 cm−1 for 1 and J1 = −5.91 cm−1, J2 = −0.98 cm−1, zJ = 1.71 for 2 above 30 K. The positive zJ values indicate the presence of weak ferromagnetic interactions between the trinuclear units via acetate bridges in 1 and 2.
TL;DR: A two-dimensional manganese-octacyanoniobate based magnet, MnII3[NbIV(CN)8]2(4-aminopyridine)10(4amopyridinium)2·12H2O, was prepared in this article, which shows a spin-flip transition with a critical magnetic field value of ca. 200 Oe.
Abstract: A two-dimensional manganese-octacyanoniobate based magnet, MnII3[NbIV(CN)8]2(4-aminopyridine)10(4-aminopyridinium)2·12H2O, was prepared. This compound shows a spin-flip transition with a critical magnetic field value of ca. 200 Oe, which originates from metamagnetism. In addition, an impedance measurement indicates that this compound is a super-ionic conductor with 4.6 × 10–4 S cm–1. The observed super-ionic conductivity is explained by the proton conduction (so-called the Grotthuss mechanism) through the hydrogen-bonding network, i.e., Lewis acidity of the Mn ion accelerates the deprotonation of the ligand water molecules, and then the released proton propagates via ligand water molecules, noncoordinated water molecules, and 4-aminopyridinium cations.
TL;DR: In this article, the Gibbs-Thomson effect was used to explain the magnetic nucleation-growth behavior in thermally induced transition and those in field-induced transition, respectively.
Abstract: Macroscopic anisotropy of spatial selectivity in magnetic nucleation and growth was clarified for itinerant-electron metamagnetic transition of La(Fe0.88Si0.12)13 by the time-dependent Ginzburg-Landau model combined with the Maxwell electromagnetic equation. Spontaneous generation of voltage supports symmetric growth in the longitudinal direction of the specimen as predicted by the simulation. The difference between nucleation-growth behaviors in thermally induced transition and those in field-induced transition is also elucidated. Electrical resistivity measurements also detect anisotropic growth of the induced phase. These results imply that the magnetic-dipole version of Gibbs-Thomson effect governs growth behavior.
TL;DR: In this paper, the inverse magnetocaloric effect taking place at the antiferro-to-ferromagnetic transition of (Co,Fe)MnP phosphides has been characterised by magnetic and direct ΔTad measurements.
Abstract: The inverse magnetocaloric effect taking place at the antiferro-to-ferromagnetic transition of (Co,Fe)MnP phosphides has been characterised by magnetic and direct ΔTad measurements. In Co0.53Fe0.47MnP, entropy change of 1.5 Jkg−1 K−1 and adiabatic temperature change of 0.6 K are found at room temperature for an intermediate field change (ΔB = 1 T). Several methods were used to control the metamagnetic transition properties, in each case, a peculiar splitting of the antiferro-to-ferromagnetic transition is observed.
TL;DR: In this paper, the effect of magnetic field (H) and hydrostatic pressure (P) on the order of magnetic transition of polycrystalline La0.4Bi0.3MnO3 series was reported.
Abstract: We report the effect of magnetic field (H) and hydrostatic pressure (P) on the order of magnetic transition of polycrystalline La0.4Bi0.3Sr0.3MnO3 which undergoes a first-order paramagnetic (PM) to ferromagnetic (FM) transition in La0.7−xBixSr0.3MnO3 series. The ferromagnetic Curie temperature (TC) increases with increasing H (12.01 K/T-cooling and 10.28 K/T-warming) and P (8.1 K/kbar-cooling and 6 K/kbar-warming). The first-order FM transition becomes second-order under the applied magnetic field of 9 T and pressure of 9.1 kbar. We have analyzed the critical behavior associated with the second order PM-FM transition at 9.1 kbar. The estimated critical exponents (β = 0.5217, γ = 1.209, and δ = 3.162) are found to be close to the mean-field model. Pressure suppresses metamagnetic transition in magnetization isotherms observed above TC in ambient pressure and enhances the magnetic entropy change (ΔSm). The ΔSm was found to increase by 50% under hydrostatic pressure of 9.1 kbar at TC = 240 K. This study sugg...
TL;DR: In this article, the magnetic phase diagram of a ground state for graphene nanoflakes of bow-tie shape and various sizes in external in-plane magnetic field is studied theoretically for the electronic structure of the systems in question.
Abstract: The magnetic phase diagram of a ground state is studied theoretically for graphene nanoflakes of bow-tie shape and various sizes in external in-plane magnetic field. The tight-binding Hamiltonian supplemented with Hubbard term is used to model the electronic structure of the systems in question. The existence of the antiferromagnetic phase with magnetic moments localized at the sides of the bow-tie is found for low field and a field-induced spin-flip transition to ferromagnetic state is predicted to occur in charge-undoped structures. For small nanoflake doped with a single charge carrier, the low-field phase is ferrimagnetic and a metamagnetic transition to ferromagnetic ordering can be forced by the field. The critical field is found to decrease with increasing size of the nanoflake. The influence of diagonal and off-diagonal disorder on the mentioned magnetic properties is studied. The effect of off-diagonal disorder is found to be more important than that of diagonal disorder, leading to significantly widened distribution of critical fields for disordered population of nanoflakes.
TL;DR: The effect of hydrostatic pressure on resistivity and magnetic ac susceptibility has been studied in Mn-doped CdGeAs2 room-temperature (RT) ferromagnetic chalcopyrite with two types of MnAs micro-clusters as mentioned in this paper.
Abstract: The effect of hydrostatic pressure on resistivity and magnetic ac susceptibility has been studied in Mn-doped CdGeAs2 room-temperature (RT) ferromagnetic chalcopyrite with two types of MnAs micro-clusters. The slight increase of temperature by about 30 K in the region between RT and Curie temperature TC causes a significant change in the positions of pressure-induced semiconductor-metal transition and magnetic phase transitions in low pressure area. By conducting measurements of the anomalous Hall resistance in the field H ≤ 5 kOe, we present experimental evidence for pressure-induced metamagnetic-like state during the paramagnetic phase at pressure P ≈ 5 GPa.
TL;DR: In this paper, magnetization, resistivity, and thermopower in the charge-orbital ordered antiferromagnet Nd0.75Na0.25MnO3.
Abstract: We report magnetization, resistivity, and thermopower in the charge-orbital ordered antiferromagnet Nd0.75Na0.25MnO3. Magnetic-field induced collapse of antiferromagnetism is found to be accompanied by a giant negative magnetothermopower (=80%–100% for a field change of 5 T) over a wide temperature (T = 60–225 K) and giant magnetoresistance. While the field-induced metamagnetic transition in magnetization is reversible upon field-cycling at T > 40 K, it is irreversible at lower temperatures and this has impact on magnetoresistance, magnetothermopower as well as change in the temperature of the sample. Our results indicate high sensitivity of thermopower to changes in the magnetic state of the sample.
TL;DR: The isolation and characterization of four coordination polymers obtained by direct reactions of metal ion salts of Cu(II), Co (II) and Fe(II) with pyrazine (pyz) and benzoic/benzoate (Bz) ligands under hydrothermal or hydroThermal microwave conditions are described.
Abstract: The isolation and characterization of four coordination polymers obtained by direct reactions of metal ion salts of Cu(II), Co(II) and Fe(II) with pyrazine (pyz) and benzoic/benzoate (Bz) ligands under hydrothermal or hydrothermal microwave conditions are described. The use of copper(II) perchlorate as the starting salt allows us to obtain compounds in a selective way by changing the pH values giving rise to the formation of two 3D-coordination polymers: [Cu(pyz)2]ClO4·pyz (1) and [Cu2(pyz)4](ClO4)2·HBz·H2O (2). In both polymers, 4-connected Cu(I) uninodal coordination networks with significant structural differences between them, due to the templating effect of the solvation molecules and counterions, have been found. However, reactions carried out under similar conditions with MSO4 (M = Co and Fe) led to the isolation of two [M2(μ-Bz)2(μ-pyz)2(Bz)2]·(HBz) isostructural infinite 1D ladder chains (M = Co (3) and M = Fe (4)). These coordination polymers show a spin-canting antiferromagnetism and metamagnetism behaviour for Co(II) and HS ↔ HS/LS ↔ LS spin-crossover phenomena for Fe(II), respectively. The latter compound is the first example of a FeIIO4N2 coordination environment showing this phenomenon.
TL;DR: In this paper, it was found that the polycrystalline NdRu2Ge2 undergoes two successive magnetic transitions at Tt and Tt = 10 and 19 kOe, respectively.
Abstract: It is found that the polycrystalline NdRu2Ge2 undergoes two successive magnetic transitions at Tt = 10 K and TN = 19 K. Evidence of metamagnetic transition is detected in the magnetization isotherm data in the antiferromagnetic regime. Temperature dependence of magnetoresistance (MR) shows that the relative magnitudes of MR at TN and Tt change considerably as the field is increased from 10 kOe to 30 kOe. Moreover, the MR is found to be positive below 9 K for 30 kOe field although the material is ferromagnetic at these temperatures. The highest value of negative MR near TN is about 42% in a field of 30 kOe, while the positive MR is about 35% at 3 K in a field of 50 kOe. Like MR, the magnetocaloric effect (MCE) at TN and Tt also shows anomalous behavior. The relative magnitudes of MCE at these temperatures are found to change with increase in field. It appears that the high field (>10 kOe) magnetic state below TN is complex, giving rise to some antiferromagnetic-like fluctuations, affecting the MR and MCE b...
TL;DR: In this article, the magnetization and transport properties of iron-phthalocyanine molecular conductors were investigated under pulsed high magnetic fields up to 55 T, where conductivity is enhanced.
Abstract: The magnetization and transport properties of iron-phthalocyanine molecular conductors are investigated under pulsed high magnetic fields up to 55 T. The metamagnetic transition is observed at approximately 14 T, where conductivity is enhanced. Below this transition, the tan δ (=e′′/e′) in the dielectric constants shows a monotonic decrease as the magnetic field strength increases, indicating that the magnetic field stabilizes the charge order. On the verge of this transition, the dielectric constants show a hysteresis below the weak-ferromagnetic transition temperature (6 K), suggesting that the π-electron charge order contributes to the weak ferromagnetism.
TL;DR: In this paper, the authors investigated the metamagnetic transition of the antiferromagnet CeAuSb2 using isothermal magnetization M(H), transverse magnetoresistivity ρt(H) and Hall resistivities ρH(H).
Abstract: CeAuSb2 has previously been classified as an antiferromagnet with moderately enhanced electron masses. As the magnetic order is suppressed by a magnetic field, non-Fermi liquid behaviour has been shown to emerge, suggesting the presence of a quantum critical point (QCP). Within the ordered phase a metamagnetic transition was detected. Here we investigate the material by isothermal magnetization M(H), transverse magnetoresistivity ρt(H) and Hall resistivity ρH(H) measurements. We show that the metamagnetic transition splits into two first order transitions below 2 K. Pronounced anomalies in ρt(H) and ρH(H) are not only observed at the QCP and the metamagnetic transitions but also at a new characteristic field above the QCP.
TL;DR: Hall effect measurements were performed under pressure and magnetic field up to 2.2 GPa and 16 T on a single crystal of UCoAl and the Hall signal is linear at low field and shows a step-like anomaly at the transition, with only little change of the Hall coefficient.
Abstract: Hall effect measurements were performed under pressure and magnetic field up to 2.2 GPa and 16 T on a single crystal of UCoAl. At ambient pressure, the system undergoes a first order metamagnetic transition at the critical field \(B_{\text{m}}=0.7\) T from a paramagnetic ground state to a field-induced ferromagnetic state. The Hall signal is linear at low field and shows a step-like anomaly at the transition, with only little change of the Hall coefficient. The anomaly is sharpest at the temperature of the critical end point \(T_{0}=12\) K above which the first order metamagnetic transition becomes a crossover. Under pressure \(B_{\text{m}}\) increases and \(T_{0}\) decreases. The step-like anomaly in the Hall effect disappears at \(P_{\text{M}} \approx 1.3\) GPa and the metamagnetic transition is not detected above the quantum critical end point (QCEP) at \(P_{\Delta}\approx 1.7\) GPa, \(B_{\text{m}}\approx 7\) T. Using magnetization data, we analyse our Hall resistivity data at ambient pressure in order...
TL;DR: In this article, the magnetic properties of slightly doped multiferroic TbMnO3 after application of a magnetic field were investigated. But the authors focused on compositions Tbmn1−xAxO3 (x ≥ 0.1) with A = ǫ, Ga, Sc, Co and Al.
TL;DR: In this article, a new cobalt polyborate with unknown crystal structure was synthesized by boric acid flux method in a sealed system, and the purity was carefully checked by Le Bail fitting of its powder XRD with good convergence.