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Showing papers on "Metamagnetism published in 1994"


Journal ArticleDOI
TL;DR: In this paper, the susceptibility and high field magnetization have been measured for Y(Co1−xMx)2 (M=Al, Fe, and Ni), and the experimental results are discussed with a new theory based on a spin fluctuation model.
Abstract: Susceptibility and high field magnetization have been measured for Y(Co1−xMx)2 (M=Al, Fe, and Ni). YCo2 exhibits a metamagnetic transition at 69 T. Ni doping in YCo2 increases the critical field (Bc), while Fe doping decreases it. These changes can be elucidated with the band picture of metamagnetism. Bc of YCo2 exhibits a positive shift proportional to the square of temperature. In the paramagnetic region of Y(Co1−xAlx)2 with x≤0.11, the susceptibility is enhanced with Al and a sharp metamagnetic transition with lower Bc is observed. The susceptibility becomes maximum at a finite temperature Tmax. Bc in the ground state is proportional to Tmax. These experimental results are discussed with a new theory based on a spin fluctuation model. The susceptibility and the metamagnetic transition are found to be very sensitive to pressure.

116 citations


Journal ArticleDOI
TL;DR: Giant magnetoresistance (GMR) effects are observed in several classes of bulk magnetic materials as discussed by the authors, and the most spectacular resistance variations are connected with metamagnetic transitions in U‐intermetallic antiferromagnets.
Abstract: Giant magnetoresistance (GMR) effects are observed in several classes of bulk magnetic materials. The resistance changes at metamagnetic transitions connected with reorientation of 4f moments are only moderate due to the relatively weak coupling of the 4f and conduction electrons. Much larger GMR effects can be achieved by mechanisms involving the d states (RhFe, RCo2), though the most spectacular resistance variations are connected with metamagnetic transitions in U‐intermetallic antiferromagnets. This phenomenon can be interpreted as due to Fermi surface gapping (due to magnetic superzones) and/or due to spin‐dependent scattering in analogy with magnetic multilayers.

57 citations


Journal ArticleDOI
TL;DR: In this article, the magnetic a and c axes are switched by applying high magnetic field in a single crystal and the switching cycle is quantitatively explained by the first order phase transition model.
Abstract: The magnetic a and c axes are switched by applying high magnetic field in ${\mathrm{DyCu}}_{2}$ single crystal. The virgin state has the Ising axis along the a direction with the two-step metamagnetism but the Ising axis is switched to the c direction by applying the field higher than 13 T along the c axis. The recovery of the virgin state is obtained either by increasing temperature above 100 K or applying the field higher than 5 T to the a axis. The switching cycle is quantitatively explained by the first order phase transition model.

34 citations


Journal ArticleDOI
TL;DR: The ternary intermetallics R6Fe13X (R = Pr, Nd; X = Cu, Sb, Bi) all crystallize in the tetragonal Nd6Fe14Si structure.

28 citations


Journal ArticleDOI
TL;DR: ErRu2Si2, ErOs 2Si2 and DyRu 2 Si2 have been investigated by magnetization, neutron diffraction, and Mossbauer measurements as discussed by the authors.

20 citations


Journal ArticleDOI
TL;DR: In this paper, a clear metamagnetic step is observed at 18 T along the a-axis for 1.3 K. The angular dependence of the step-magnetization shows a large anisotropy in the a c -plane and the spin system can be described by the X Y -spin model except for very small anisotropic in the c-plane.
Abstract: The high field magnetization of antiferromagnetic heavy Fermion material UPd 2 Al 3 is investigated up to 50 T. A clear metamagnetic step is observed at 18 T along the a -axis for 1.3 K. The angular dependence of the step-magnetization shows a large anisotropy in the a c -plane and the spin system can be described by the X Y -spin model except for very small anisotropy in the c -plane. The observed step-magnetization is explained by introducing the model that the heavy Fermion state is broken at the critical field by the magnetic field and the exchange interaction is modified by the change in the carrier density.

19 citations


Journal ArticleDOI
TL;DR: In this paper, the lattice constant, low-temperature specific heat and high-field magnetization of the Laves-phase itinerant electron metamagnets Lu(Co1-xSix)2 have been investigated.
Abstract: The lattice constant, low-temperature specific heat and high-field magnetization of the Laves-phase itinerant electron metamagnets Lu(Co1-xSix)2 have been investigated. By partial substitution of Co by Si, the critical field Hc of the metamagnetic transition decreases and the temperature Tmax of the magnetization maximum shifts to lower temperatures with increasing x regardless of the decrease in the lattice constant. Both the electronic specific heat coefficient gamma and the magnetic susceptibility chi increase with increasing x up to x=0.09 and decrease above this concentration. The present results suggest that the decrease in the critical field is not due to the increase in the lattice constant but is due to the hybridization between 3d electrons of Co and 3p electrons of Si.

17 citations


Journal ArticleDOI
TL;DR: In this article, the average exchange parameter between Nd and Co is estimated to be JNdCo = 2.0 × 10-22 J. The compound exhibits two metamagnetic transitions of the Co sublattice to a higher moment state.
Abstract: Magnetization measurements have been carried out for Y1−xNdxCo3 compounds with 0⩽x⩽1 in ultrahigh magnetic fields up to 110T. The compound exhibits two metamagnetic transitions of the Co sublattice to a higher moment state. Both transition fields decrease with increasing Nd concentration due to the exchange field from the Nd sublattice acting on the Co sublattice. From the concentration dependence of the transition fields the average exchange parameter between Nd and Co is estimated to be JNdCo = 2.0 × 10-22 J. The spontaneous Co moment and the Curie temperature also exhibit an anomalous increase with Nd concentration, which originates from the transitions.

14 citations


Journal ArticleDOI
TL;DR: For a number of Y(Co, Al) 2 and (R, Y)Co 2 compounds, the effects of external and internal (molecular) fields on the resistivity are accentuated.

13 citations


Journal ArticleDOI
TL;DR: In this paper, the Laves phase Lu(Co 1− x M x ) 2 (M = Ga, Sn and Si) compounds exhibit itinerant electron metamagnetism for small x.
Abstract: High field magnetizations up to 100 T, lattice constants and electronic specific heat coefficients have been measured for the Laves phase Lu(Co 1− x M x ) 2 (M = Ga, Sn and Si) compounds which exhibit itinerant electron metamagnetism for small x . The lattice constant increases with increasing x for M = Ga, or Sn, while it decreases linearly in the case of M = Si. The metamagnetic characteristics strongly depend on the substitutional element M. The critical field for the metamagnetic transition decreases with increasing x for M = Ga and Si, whereas it remains constant around 40 T above x = 0.06 for M = Sn. The magnetization jump due to the transition increases for M = Sn and rapidly decreases for M = Si. The different characteristics may result from the difference in the shape of the density of states modified by the substitutional element.

12 citations


Journal ArticleDOI
TL;DR: In this paper, the magnetization of powdered RMn/sub 6-x/Cr/sub x/Ge /sub 6/-compounds (with R=Y, Gd, Tb, Dy, Ho, Er, Lu) was studied at 4.2 K in high magnetic fields up to 38 T.
Abstract: The magnetization of powdered RMn/sub 6-x/Cr/sub x/Ge/sub 6/-compounds (with R=Y, Gd, Tb, Dy, Ho, Er, Lu) was studied at 4.2 K in high magnetic fields up to 38 T. From the high field data values for the Mn-moments were obtained for compounds with K=Y, Gd, Tb, Dy whereas the R-Mn coupling constants were estimated for the compounds with R=Gd, Tb, Dy. The Mn-moments were found to be approximately 2/spl musub B/. Metamagnetism was observed in compounds with R=Y, Lu. The Mn-Mn distance strongly affects the magnetization curves in these latter eases. >

Journal ArticleDOI
TL;DR: In this article, the magnetization of Y 1−x Nd x Co 3 (0 ≤ x ≤ 1) was measured up to 110 T. The volume magnetostriction was measured in high magnetic field up to 40 T with a capacitance method.
Abstract: The magnetization of Y 1−x Nd x Co 3 (0 ≤ x ≤ 1) was measured up to 110 T. YCo 3 exhibits two successive transitions to a higher moment state of Co. When a part of Y is replaced with Nd, two transition fields decrease owing to the positive exchange interaction between Nd and Co. From these results, the exchange interaction parameter between Nd and Co has been evaluated to be 2.13x10 −22 J. The volume magnetostriction was measured in high magnetic field up to 40 T with a capacitance method. A large volume change has been observed with the growth of the Co moment.

Journal ArticleDOI
TL;DR: A survey of the main properties associated with incommensurate (amplitude modulated) structures in rare earth magnetic systems is presented in this article, where the authors consider only the crystal field effects and the bilinear exchange coupling, and a self-consistent Periodic Field model explains quantitatively all the observed features: the thermodynamical properties, the metamagnetism, the multistep behaviour, the complex phase diagrams, the locking of the structures onto a commensurate configuration with a short periodicity at low temperature, the high field resurgence of the

Journal ArticleDOI
TL;DR: In this paper, a magnetic and Mossbauer spectroscopy study of nonoriented and magnetically oriented samples of Nd6Fe13Sn was performed and strong evidence for antiferromagnetic spin arrangements in the iron magnetic sublattice and antiferrome magnetism of the Nd moments with only a small contribution to the net magnetization in fields up to 14 T was found.
Abstract: A magnetic and Mossbauer spectroscopy study of nonoriented and magnetically oriented samples of Nd6Fe13Sn was performed. At 4.2 K a metamagnetic transition takes place in a field of 7.1 T. Strong evidence for antiferromagnetic spin arrangements in the iron magnetic sublattice and antiferromagnetism of the Nd moments with only a small contribution to the net magnetization in fields up to 14 T was found.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the dynamic properties of metamagnetic transition in FeTiO 3 by monitoring the time-dependent change in magnetization of the spherical single crystal and found that the time evolution of the magnetization at the transition was extremely slow; the relaxation time at 4.2 K reaches more then 15 min when the external field was suddenly increased from 70 kOe (H c ≈kOe) to 82.3k Oe ( > H c ).
Abstract: Dynamical properties of metamagnetic transition in FeTiO 3 have been investigated by monitoring the time-dependent change in magnetization of the spherical single crystal. The time evolution of the magnetization at the transition was found to be extremely slow; the relaxation time at 4.2 K reaches more then 15 min when the external field was suddenly increased from 70 kOe ( H c ≈kOe) to 82.3 kOe ( > H c ). Systematic difference in the time dependence has been found in the antiferromagnetic to ferromagnetic (increasing field) and ferromagnetic to antiferromagnetic transition (decreasing field). Forced magnetostriction has also been measured at 4.2K; a discontinuous change in length along the hexagonal c -axis at the metamagnetic transition amounts to 0.0%, to which the slow relaxation of the magnetization may be ascribed.

Journal ArticleDOI
TL;DR: In this article, the memory of position and shape of antiferromagnetic domains, which first grow from the more magnetized phase by field decreasing, is preserved even after cycling through Ha = 0 as a consequence of random-field induced nano-domain structures.

Journal ArticleDOI
TL;DR: In this paper, the effects of Ni and Fe substitutions on the metamagnetic property of the Laves phase intermetallic compound YCo 2 were studied in pulsed magnetic fields up to 110T.
Abstract: Effects of Ni and Fe substitutions on the metamagnetic property of the Laves phase intermetallic compound YCo 2 are studied in pulsed magnetic fields up to 110T. A linear increase in the critical field B c is observed for the Ni substitution, whereas the Fe doping is found to lower B c . The results are qualitatively in accordance with the band picture of metamagnetism.

Journal ArticleDOI
TL;DR: In this paper, the effect of the molecular field from the Gd sublattice on the itinerant metamagnetism of the Co sub-layer is studied.
Abstract: The magnetization of polycrystalline Y1-tGdtCo3 with 0

Journal ArticleDOI
S. Misawa1
TL;DR: In this article, the magnetic susceptibility for paramagnetic or ferromagnetic metals carrying itinerant electrons is evaluated as a function of temperature, and it is shown that for the paramagnetic regime, at low temperatures, the susceptibility definitely shows a maximum which is responsible for universal phenomena observed in 4d and 5d metals, Laves phase compounds and heavy-fermion compounds.
Abstract: On the basis of the Fermi-liquid model the magnetic susceptibility for paramagnetic or ferromagnetic metals carrying itinerant electrons is evaluated as a function of temperature. It is shown that for the paramagnetic regime, at low temperatures, the susceptibility definitely shows a maximum which is responsible for universal phenomena observed in 4d and 5d metals, Laves phase compounds and heavy-fermion compounds. The present model explains the concurrence of the susceptibility maximum and Curie-Weiss susceptibility in nearly ferromagnetic metals, the appearance of thermally induced ferromagnetism and the precise Curie-Weiss law for relatively weak ferromagnets. The Fermi-liquid effect produces logarithmic terms in the free energy with respect to temperature, magnetization M etc. Because of the M 4 In M term of the energy, some Laves phase compounds are shown to exhibit a metamagnetic transition. This term is also the origin of peculiar nonlinear magnetization curves observed for CeRu2Si2.

Journal ArticleDOI
TL;DR: In this paper, the magnetic order of the cobalt atoms of UCo2P2 was investigated with a SQUID magnetometer and by neutron diffraction, and the nuclear structure of this tetragonal CaBe2Ge2-type compound was confirmed by Rietveld refinements.

Journal ArticleDOI
TL;DR: In this paper, the magnetization of the f-d ferrimagnet Y 0.75 Tm 0.25 (Co 0.88 Al 0.12 ) 2 with an unstable metamagnetic itinerant d-subsystem in the strongly ferromagnetic state was measured up to 38 T at 4.2 K.

Journal ArticleDOI
TL;DR: In this article, the phase diagram of DyFeO 3 in the presence of a magnetic field in the crystallographic ( ab ) plane was determined by means of magnetic and magneto-optic studies performed in the temperature range 1.7-6 K.

Journal ArticleDOI
TL;DR: In this paper, the authors describe recent research activities in the high-field magnetism mainly done in the Research Center for Extreme Materials, Osaka University with a short survey of the history.
Abstract: This paper describes recent research activities in the high field magnetism mainly done in the Research Center for Extreme Materials, Osaka University with a short survey of the history. The main activities are concentrated on the condensed matter physics covering the fields of magnetism and superconductivity where a common keyword is highly correlated electron physics. A rich variety in the metamagnetism, field-induced electronic transitions under high field is summarized. Multistep magnetization in CeP between 20 and 60 T is introduced as a typical example of the case where the phase transition has relation to the de Haas-van Alphen effect. Measurement of electron spin resonance (ESR) in heavy fermion URu 2 Si 2 around 20 T gives information on both the conduction- and the f-electron densities on the U-site. UPd 2 Al 3 is investigated and the meta-magnetism is analyzed with the assumption that the heavy fermion state releases conduction electrons at the critical field. New frontiers in the high field technologies are established with a highly sensitive magnetometer using the dynamical Faraday effect.

Journal ArticleDOI
TL;DR: In this paper, high-field magnetization measurements up to 38 T have been performed on a newly grown single-crystalline Ho/sub 2/Co/sub 17/ sample along the main crystallographic directions of the hexagonal cell.
Abstract: High-field magnetization measurements up to 38 T have been performed on a-newly-grown single-crystalline Ho/sub 2/Co/sub 17/ sample along the main crystallographic directions of the hexagonal cell. The magnetization curve along the easy direction (b-axis) exhibits a metamagnetic-like transition at 23.6 T whereas for the a-axis a similar transition occurs at 32.4 T. The transitions are extremely sharp-much sharper than in previously grown crystals. The transitions are understood as a moment-flip transition associated with the formation of a noncollinear magnetic structure in this ferrimagnetic compound. From the transition-field value the 3d-4f spin-exchange parameter has been derived. Magnetization under pressure up to 5 kbar has been used to determine the pressure dependence of the magnetic transition at 23.6T. The pressure dependence dB/sub tr//dP amounts to -24 TMbar/sup -1/. >

Journal ArticleDOI
TL;DR: In this paper, the minimal value of the energy in the Stoner model is calculated in the context of itinerant-electron metamagnetism, using an elliptic density of states.
Abstract: Electronic energy in the context of itinerant-electron metamagnetism is considered in a new way. In particular, the minimal value of this energy is calculated within the Stoner model. To get this end, an elliptic density of states is used.

Journal ArticleDOI
TL;DR: In this paper, a single crystal was measured at 4.2 K in magnetic fields up to 14 T and the metamagnetic transition was observed at magnetic field H m = 9 T. The occurrence of the transition may be related to the collective electron metamagnetism.

Journal ArticleDOI
TL;DR: In this article, the SU(4) Kondo model was used to report the magnetization process with the exact solution at the ground state in UPd 2 Al 3 and the crystalline field parameters used were inferred from those determined by the experimental data.
Abstract: We report the magnetization process with the SU(4) Kondo model (the single site Coqblin-Schrieffer model) taking into account the four 5 f -levels from the lowest level split by the hexagonal crystalline field of the total spin J =4. We treat the model with the exact solution at the ground state. As an example, we investigate how far the theoretical result is fitted into the experimental results in UPd 2 Al 3 within this approach. The crystalline field parameters used are inferred from those determined by the experimental data.