Showing papers on "Metamagnetism published in 1995"
TL;DR: The physical properties of the heavy fermion compound CeRu 2 Si 2 are reviewed in this article, where a metamagnetic-like transition occurs at a field H M of 7.7 T and the strong coupling between this effect and the volume leads to a quasi-collapse of the lattice.
Abstract: The physical properties of the heavy fermion compound CeRu 2 Si 2 are reviewed. Since this compound is close to a magnetic instability, special attention is paid to its magnetization in which a metamagnetic-like transition occurs at a field H M of 7.7 T and to the strong coupling between this effect and the volume, leading to a quasi-collapse of the lattice. It is shown that the value of the differential susceptibility at H M reaches an intrinsic finite limit at very low temperature. Different theoretical models are discussed.
67 citations
TL;DR: In this paper, the strong interplay between lattice, electronic and magnetic properties in CeRu 2 Si 2 is emphasized and the broadening of the metamagnetic transition is discussed.
Abstract: The strong interplay between lattice, electronic and magnetic properties in CeRu 2 Si 2 is emphasized. Special attention is given on the broadening of the metamagnetic-like transition. Comparison is made with similar phenomena in other heavy fermion cerium compounds: CeCu 6 , CeAl 3 .
35 citations
TL;DR: In this paper, the effect of spin fluctuations on the metamagnetic transition in an itinerant-electron system is discussed at finite temperature, and the critical pressure of the MT is shown to decrease with increasing temperature.
31 citations
TL;DR: A survey of metamagnetic processes discovered during recent decades in rare earth intermetallics, where only the rare earth is magnetic, is presented together with macroscopic and microscopic aspects of the complex associated H-T magnetic phase diagrams as discussed by the authors.
30 citations
TL;DR: In this article, a phenomenological model for the metamagnetic transition in intermetallic alloy compounds near the paramagnetic side of the ferromagnetic instabilities such as YCo2 with Al doping is proposed.
Abstract: We propose a phenomenological picture for the mechanism of the metamagnetic transition often observed in intermetallic alloy compounds near the paramagnetic side of the ferromagnetic instabilities such as YCo2 with Al doping. The present treatment assumes the magnetization process is described in terms of the spin fluctuation spectrum, in clear contrast with the previous approaches based on the Hartree-Fock approximation assuming the fine structure of the density of states curve around the Fermi energy.
23 citations
TL;DR: In this article, a detailed study of the magnetic properties of TbRu 2 Ge 2 and TbRRu 2 Si 2 single crystals is presented, from specific heat and magnetization measurements.
Abstract: A detailed study of the magnetic properties of TbRu 2 Ge 2 and TbRu 2 Si 2 single crystals is presented, from specific heat and magnetization measurements. Both compounds exhibit very similar features, in particular a multistep metamagnetic behaviour at low temperature along the [001] easy direction, and the occurrence of a zero-field phase transition at a temperature far below the Neel temperature. The complex H-T magnetic phase diagrams are deduced, a situation typical of long-period commensurate or incommensurate systems.
22 citations
TL;DR: In this article, a detailed study of the magnetic properties of the tetragonal rare earth compound DyRu2Si2 is presented, where magnetization measurements on a single crystal as well as specific heat and resistivity measurements on polycrystal show features which are typical of a long-period commensurate system in the presence of a huge uniaxial anisotropy.
Abstract: A detailed study of the magnetic properties of the tetragonal rare earth compound DyRu2Si2 is presented. Magnetization measurements on a single crystal as well as specific heat and resistivity measurements on a polycrystal show features which are typical of a long-period commensurate system in the presence of a huge uniaxial anisotropy. Multistep metamagnetism occurs below the Neel temperature TN=29 K, in particular at low temperatures. In the low-field low-temperature region, a new magnetic phase has been discovered with an anomalous behaviour.
21 citations
TL;DR: Magnetic properties of the UCo 0.9 T 0.1 Al quasiternary solid solutions (T = Fe, Ni, Ru and Pd) have been studied in this paper.
20 citations
TL;DR: Magnetization curves obtained on a tetragonal GdRu 2 Si 2 single crystal along the [100] and [001] axes are presented in this article, where they exhibit several metamagnetic transitions and a strong anisotropy, a behaviour quite unusual in a Gd compound.
19 citations
TL;DR: The structure of EuZnGe as discussed by the authors belongs to the ZrBeSi-type, a ternary ordered version of the AlB 2 -type, and it was refined from single-crystal diffractometer data to wR2 = 0.0297 for 146 F 2 values and eight variables.
Abstract: Crystals of EuZnGe were prepared by a reaction of the elemental components in tantalum tubes. EuZnGe crystallizes in the hexagonal space group P6 3 /mmc with the lattice constants a = 437.2(1) pm, c = 860.4(2) pm and V = 0.1424(1) nm 3 . The structure belongs to the ZrBeSi-type, a ternary ordered version of the AlB 2 -type. It was refined from single-crystal diffractometer data to wR2 = 0.0297 for 146 F 2 values and eight variables. The crystal chemistry of EuZnGe is discussed in comparison with the structure of binary EuGe 2 . Susceptibility measurements show Curie-Weiss behavior above 40 K with μ exp = 7.8(1)μ B /Eu, indicating Eu 2+ . Below 0.01 T EuZnGe shows two magnetic transitions at 12.2(5) K and 9.5(5) K, respectively. Magnetization measurements at 2K indicate metamagnetism with a critical field of 0.60(5) T. The saturation magnetic moment per Eu atom at 2 K is 5.8(1) μ B .
18 citations
TL;DR: In this paper, a comparison of the magnetic properties of polymeric diazine-bridged complexes, Ni(pyz)2X2 (X = Cl or NO3), Ni(mepyz)4(NO3)2•H2O and Ni(p-CH3C6H4SO3) 2•H 2O with those of related monometallic systems was made.
Abstract: Several nickel(II) complexes containing pyridine (py), pyrazine (pyz) or methylpyrazine (mepyz) have been synthesized and characterized by vibrational and electronic spectroscopy, differential scanning calorimetry, and magnetic susceptibility studies to cryogenic temperatures. A comparison of the magnetic properties of the polymeric diazine-bridged complexes, Ni(pyz)2X2 (X = Cl or NO3), Ni(pyz)(p-CH3C6H4SO3)2, Ni(mepyz)(NO3)2, and Ni(pyz)3(CH3SO3)2•CH3OH with those of the related monometallic systems, Ni(py)4X2 (X = Cl, p-CH3C6H4SO3 or CH3SO3) and Ni(mepyz)4(NO3)2•H2O provides evidence for weak antiferromagnetic coupling between metal centers mediated by bridging diazine ligands in the former group of compounds. The magnetic properties were analyzed employing a model for S = 1 which takes into account zero-field splitting and employs a molecular field term to account for weak magnetic exchange. The compounds Ni(pyz)Cl2 and Ni(py)Cl2 show metamagnetic behaviour with critical fields of 13 and 2 kOe, respect...
TL;DR: In this paper, a metamagnetic transition in PrCu 2 where a cooperative Jahn-Teller effect occurs below 8 K was observed, which brought about a conversion between an easy and a hard axes in magnetization, which is reflected in a drastic change of the de Haas-van Alphen amplitude.
Abstract: We have observed a metamagnetic transition in PrCu 2 where a cooperative Jahn-Teller effect occurs below 8 K. This transition brings about a conversion between an easy and a hard axes in magnetization, which is reflected in a drastic change of the de Haas-van Alphen amplitude, that is a change of the scattering lifetime of conduction electrons. The origin of the metamagnetic transition is ascribed to a quadrupole moment of the 4 f level.
TL;DR: Two successive metamagnetic transitions have been observed in single crystals of Y 2 Cu 2 O 5 at B c 1 = 3.0 T and B c 2 = 4.8 T for B∥b-axis, above which the magnetization gradually increases and saturates at B s = 7.2 T.
Abstract: Two successive metamagnetic transitions have been observed in single crystals of Y 2 Cu 2 O 5 at B c1 = 3.0 T and B c2 = 4.8 T for B∥b-axis, above which the magnetization gradually increases and saturates at B s = 7.2 T. The most interesting point in this study is that the metamagnetic transition has not been supposed in the Cu 2+ spin system due to the small anisotropy and never observed in copper compounds so far
TL;DR: In this article, the structure and magnetic properties of TbMn6Sn6 have been investigated and it was found that the magnetization values first increase with increasing temperature, next exhibit a peak and then decrease with further increase in temperature.
Abstract: In the present paper, the structure and magnetic properties of TbMn6Sn6 have been investigated. TbMn6Sn6 is found to be of HfFe6Ge6-type structure (space group P6/mmm) with a = 5.5461 Angstrom, c = 9.0477 A and V = 241 Angstrom(3). This compound shows ferrimagnetic behaviour with the ordering temperature T-c = 421 K. A peak is also observed in the thermal magnetic curve at 330 K. Under magnetic fields of 100, 300 and 400 Oe, the magnetization values first increase with increasing temperature, next exhibit a peak and then decrease with further increase in temperature. When the applied magnetic field is sufficiently large, e.g. 1000 and 2100 Oe, the magnetization of the whole sample decreases with increasing temperature. With increasing temperature from the range 77-300 K, the coercivity first increases, next undergoes a peak at about 200 K and then decreases. At room temperature a magnetization jump is observed in the magnetization curves at a field of about 4 kOe in both the aligned and the free powder samples. This jump may be attributed to the spin-flop or metamagnetic transition. The magnetic anisotropy field at room temperature is found to be 8.33 kOe.
TL;DR: In this article, the antiferromagnetic compound UNiGa was measured at 4.2 K on a single crystal in a magnetic field applied along the c axis, with negligible volume effect owing to cancellation of the linear strains.
TL;DR: The magnetic properties of the carbides RCoC (R = Y, Gd-Er, Lu) were determined with a SQUID magnetometer between 2 and 300 K at magnetic flux densities of ± 5.5 T as discussed by the authors.
TL;DR: In this article, high-field magnetization measurements at 4.2 K on several U2T2X (T = Ni, Rh, Pd, Pt; X = In, Sn) compounds have been performed on free and fixed powders up to 57 T.
Abstract: High-field magnetization measurements at 4.2 K on several U2T2X (T = Ni, Rh, Pd, Pt; X = In, Sn) compounds have been performed on free and fixed powders up to 57 T. An antiferromagnetic ground state of U2Ni2Sn is corroborated by metamagnetic transitions at 30, 39 and 51 T. U2Rh2Sn shows one metamagnetic transition at 21 T and U2Pd2Sn two metamagnetic transitions at 39 and 45 T. U2Pt2In shows no metamagnetism up to 57 T which is in agreement with the non-magnetic ground state of this compound. The short-pulsed measurements up to 57 T are compared with previous results obtained in quasi-static fields up to 35 T.
TL;DR: In this paper, it has been shown that the magnitude of the Haldane gap can be controlled by substituting the bridging groups and in-plane ligands with substituting a bridging group with a ligand.
Abstract: New Haldane gap compounds with S=1 have been characterized by single-crystal X-ray analyses and magnetic measurements. From these results, it has been found that the magnitude of the Haldane gaps can be controlled by substituting the bridging groups and in-plane ligands. The magnetic measurements of quasi-one-dimensional halogen-bridged binuclear Ru complexes with S=3/2. Ru2(CH3COO)4X (X=Cl, Br and 1) have revealed that the Br- and I-bridged compounds show one-dimensional antiferromagnetic interactions but no spin-Pelerls transition over the temperature range measured, while the C1-bridged compound shows no magnetic interaction among binuclear RU2 units through the bridging Cl− ions along the chain but spin-crossover behavior between S=3/2 and 1/2 in the binuclear Ru2 unit. The oxalato-bridged Fe2+ compound with S=2, Fe(ox).2Hz0 has no Haldane gap but shows metamagnetism under the high magnetic field.
TL;DR: In this paper, it was shown that the first order metamagnetic transition in high magnetic fields at T < 62 K and the existence of a FM state with T c = 74 and 250 K have been observed.
Abstract: Experiments indicate that the AF 1 phase in Mn 5 Si 3 can be suppressed by 5 kbar. Then, the AF 2 phase undergoes a transition to a ferromagnetic state. In (Mn 1−x Fe x ) 5 Si 3 samples a first-order metamagnetic transition in high magnetic fields at T < 62 K and the existence of a FM state with T c = 74 and 250 K have been observed
TL;DR: In this paper, a logarithmic form of the free energy with respect to temperature and magnetization is shown to explain all aspects of metamagnetism and the relation between the susceptibility maximum and metamaggnetism is clarified.
Abstract: Fermi liquid description of itinerant electron metamagnetism at finite temperature is presented and applied to recent experiment on Y(Co, Al)2. In contrast to the ordinary form, a logarithmic form of the free energy with respect to temperature and magnetization is shown to explain all aspects of metamagnetism. The relation between the susceptibility maximum and metamagnetism is clarified.
TL;DR: In this paper, a structural phase transition of the type Bmab (orthorhombic) → I4/mmm (tetragonal) has been observed for the RCaCrO4 (RSm or Y) stoichiometric oxides.
TL;DR: Magnetization of a series of transition metal alloys (Fe1−xTx)3Ga4 with T = Mn, V, Cr and Ti having values of x in the range 0.05⩽ x ⩽ 0.2 has been examined as a function of the magnetic field (0 − 12 T) and temperature (4 − 300 K).
Abstract: Magnetization of a series of transition metal alloys (Fe1−xTx)3Ga4 with T = Mn, V, Cr and Ti having values of x in the range 0.05 ⩽ x ⩽ 0.2 has been examined as a function of the magnetic field (0–12 T) and temperature (4–300 K). The alloys have the same base-centred monoclinic crystal structure as Fe3Ga4 and, in general, show a low field metamagnetic transition similar to that seen for Fe3Ga4. In the low temperature regime, many of the alloys also show an apparent first order transition at much higher fields (∼ 6 T) to a ferromagnetic state. The large hysteresis associated with this transition may indicate a magnetostrictive origin. Preliminary neutron diffraction results obtained at ISIS indicate that a small lattice contraction occurs in transforming to the antiferromagnetic state. The magnetic phase diagrams are interpreted in terms of theoretical results by Moriya and Usami [Solid State Commun. 23 (1977) 935] and Isoda [J. Phys. Soc. Japan 53 (1984) 3587] on magnetic phase transitions in itinerant electron systems.
TL;DR: In this paper, a cooperative Jahn-Teller effect is observed in PrCu 2 where there is a large crystal distortion and also a drastic change of the Fermi surface, which brings about a large change in the electronic state.
Abstract: We have observed a metamagnetic transition in PrCu 2 where there is a cooperative Jahn-Teller effect occurring below 8 K. This transition brings about a large crystal distortion and also a drastic change of the electronic state, namely the Fermi surface.
TL;DR: In this paper, a hexagonal GaGeLi-type crystal structure is used to construct a collinear antiferromagnets with the orthohexagonal magnetic unit cell.
TL;DR: In this article, the three-step metamagnetism in DyRu 2 Si 2 has been studied by neutron diffraction measurements on a single-crystal sample, and the magnetic structures are inferred to be two-dimensional and incommensurate.
Abstract: The three-step metamagnetism in DyRu 2 Si 2 has been studied by neutron diffraction measurements on a single-crystal sample. At 4.2 K the magnetization jumps at 10 kOe (= H c1 ), 15.5 kOe (= H c2 ) and 17.5 kOe (= H c3 ) and then reaches saturation. The compound has a one-dimensional incommensurate structure with a fundamental wave vector of Q 1 = (0.22,0,0) for H < H c1 . For H c1 ≤ H < H c2 and for H c2 ≤ H < H c3 , the magnetic structures are characterized by fundamental wave vectors of Q 1 , Q' 1 = (0,0.22,0), Q 2 = (0.22,0.22,0), Q' 2 = (0.22, - 0.22,0) and Q 0 = 0. The structures are inferred to be two-dimensional and incommensurate. Schematic representations of the magnetic structures are presented.
TL;DR: In this article, the strong domain wall pinning was found to indicate a large magnetocrystalline anisotropy at higher magnetic fields and a metamagnetic transition from a low to a high magnetization state occurs in a wide temperature regime concomitant with a large hysteresis below 150 K.
TL;DR: The magnetoelastic effect in Laves phase compounds (Gd1−xYx)Co2 in the ferrimagnetic state is very remarkable because the Co moment induced by the exchange field from Gd gives rise to a large magnetovolume effect.
01 Jan 1995
TL;DR: In this paper, a mean-field picture of the quasiparticle states of almost localized fermions and the first-order metal-insulator transitions at nonzero temperature is presented.
Abstract: We summarize a mean-field picture of the quasiparticle states of almost localized fermions and the first-order metal-insulator transitions at nonzero temperature, as well as make a comparison between theory and experiment for pure and doped V 2 O 3 systems. We also discuss some of the unresolved questions for almost localized fermions such as the spin dependence of the effective mass, the metamagnetism and the instability of the Fermi surface at the Mott localization boundary.
TL;DR: The magnetization of single crystal ErNi 2 B 2 C has been measured in the temperature range from 2 K up to 200 K and in magnetic fields up to 5 T as discussed by the authors.
Abstract: The magnetization of single crystal ErNi 2 B 2 C has been measured in the temperature range from 2 K up to 200 K and in magnetic fields up to 5 T. Performed measurements reveal a striking anisotropy both in paramagnetic and ordered states. It has been suggested that the high susceptibility near the Neel temperature is responsible for anomalies observed in the temperature dependence of the first field for flux penetration and for the irreversibility field. A cascade of metamagnetic transitions has been observed for an external field applied perpendicular to the c -axis. These transitions are discussed in the framework of the incommensurate mean-field model.