Coexistence of Nonmagnetic and Magnetic Co in Cubic Laves Phase Compounds Lu(Co1-xAlx)2

Shinogi, Akira; Saito, Takamitsu; Endo, Ken

doi:10.1143/jpsj.56.2633

Cited by 21 publications

(6 citation statements)

References 10 publications

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“…With increasing x, the spontaneous magnetization increases significantly in a limited narrow composition range. It should be pointed out that such a marked increase has not been observed in Lu(Co 1−x Al x ) 2 (Iijima et al 1990, Endo et al 1987a, Gabelko et al 1987, because non-magnetic and magnetic states of Co atoms coexist in the composition range 0.06 x 0.12 (Endo et al 1987b, Shinogi et al 1987. It is considered that the difference mentioned above comes also from the annealing conditions of the specimens as discussed in connection with figure 4.…”

Section: Resultsmentioning

confidence: 93%

“…In both compounds mentioned above, no sharp metamagnetic transition has been observed in relatively low magnetic fields because of the onset of a weak ferromagnetism in Y(Co 1−x Al x ) 2 (Aleksandryan et al 1985, Sakakibara et al 1986, 1990a and the coexistence of non-magnetic and magnetic states of Co atoms in Lu(Co 1−x Al x ) 2 (Endo et al 1987b, Shinogi et al 1987. On the other hand, it has been demonstrated that Lu(Co 1−x Ga x ) 2 compounds show a sharp itinerant-electron metamagnetic transition even in low magnetic fields (Murata et al 1993a-c) in contrast to Y(Co 1−x Al x ) 2 and Lu(Co 1−x Al x ) 2 .…”

Section: Introductionmentioning

confidence: 99%

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Itinerant-electron metamagnetism and the onset of ferromagnetism in Laves phase compounds

Saito

Yokoyama

Fukamichi

1997

J. Phys.: Condens. Matter

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Detailed magnetization measurements have been carried out for Laves phase compounds which have a C15-type structure up to x = 0.220. A clear increase in the lattice constant occurs at room temperature in the vicinity of x = 0.095, corresponding to the critical concentration of the onset of ferromagnetism. A representative first-order metamagnetic transition was observed in the compounds with x = 0.090 and 0.093 in relatively low fields below 9 T. The critical temperature from the first- to second-order metamagnetic transition in both compounds and the susceptibility maximum temperature for several paramagnetic compounds were obtained. It should be noted that practically coincides with for x = 0.093, very close to the critical concentration of the onset of ferromagnetism. This result is well explained by the recent theory associated with spin fluctuations. The temperature shifts to lower temperatures with increasing x and disappears at x = 0.095 and above, correlated with the onset of ferromagnetism also. The spontaneous magnetization per Co atom exhibits a maximum value of at x = 0.110, whereas the Curie temperature does not show a maximum value at the same composition.

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Section: Resultsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Itinerant-electron metamagnetism and the onset of ferromagnetism in Laves phase compounds

Saito

Yokoyama

Fukamichi

1997

J. Phys.: Condens. Matter

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“…For Lu(Co 1−x Al x ) 2 with x = 0.06 and 0.08, on the other hand, an extremely broad hysteresis in the metamagnetic transition curves has been observed [16]. In addition, the coexistence of paramagnetic and ferromagnetic Co atoms in the compound with x = 0.08 has been indicated by NMR experiment [27]. However, detailed considerations of magnetic properties of Lu(Co 1−x Al x ) 2 in the vicinity of the critical concentration for the onset of ferromagnetism have not been made yet.…”

Section: Introductionmentioning

confidence: 86%

Itinerant-electron metamagnetism and magneto-volume effects in Lu(Co_1-xAl_x)₂Laves phase compounds

Yokoyama

Saito

Fukamichi

et al. 2001

J. Phys.: Condens. Matter

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The itinerant-electron metamagnetic transition (MT) and the effects of hydrostatic pressure on the critical transition field BC of the MT, on the spontaneous magnetization MS and on the Curie temperature TC have been investigated for well homogenized Lu(Co1-xAlx)2 Laves phase compounds. The critical field BC decreases with increasing x, maintaining a linear relationship with the inverse susceptibility at the temperature where the susceptibility exhibits a maximum value, χ-1(Tmax). On applying pressure, the magnetization M of the ferromagnetic compound with x = 0.100 is drastically decreased at a critical pressure, resulting in a paramagnetic state. In addition, the metamagnetic transition from the paramagnetic to the ferromagnetic state is induced by applying an external magnetic field. The effect of pressure on the Curie temperature TC is extremely large and negative in the vicinity of the critical concentration for the onset of ferromagnetism. The pressure coefficient of the Curie temperature, ∂ln TC/∂P, is much larger than that of the spontaneous magnetization, ∂ln MS/∂P, below x = 0.150. These results can be explained by the theory for itinerant ferromagnets having a negative coefficient b of the fourth-order term in the Landau expansion. The Landau expansion coefficients estimated from the experimental results are in accord with the theories. From these estimated values, it is concluded that the magneto-volume effect decreases the critical transition field BC. It has been confirmed that the results for Lu(Co1-xAlx)2 are very much analogous to those for Lu(Co1-xGax)2.

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“…In some materials, magnetic cluster excitations can occur in the paramagnetic region above T c or above T N [47][48][49][50][51][52], causing the appearance of spin waves in the paramagnetic phase, for instance, in Ni, Fe, EuO, EuS, Pd 3 Fe, and Gd [53][54][55][56][57][58]. The coexistence of ferromagnetic and nonmagnetic phases was also observed in Y 2 Co 7 , YCo 3 , Co(S x Se 1−x ) 2 , Co(Ti x Al 1−x ) 2 , and Lu(Co 1−x Al x ) 2 [59,60]. In colossal magnetoresistance materials, such as La 1−x Ca x MnO 3 and La 1−x Sr x CoO 3 , one observes the coexistence of a paramagnetic insulating, or semiconducting, phase and a ferromagnetic metallic phase [61][62][63], while in La 0.67−x Bi x Ca 0.33 MnO 3 , paramagnetic and antiferromagnetic phases coexist [64].…”

Section: Introductionmentioning

confidence: 92%

Zeroth-Order Nucleation Transition under Nanoscale Phase Separation

Yukalov¹,

Yukalova²

2021

Preprint

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Materials with nanoscale phase separation are considered. A system representing a heterophase mixture of ferromagnetic and paramagnetic phases is studied. After averaging over phase configurations, a renormalized Hamiltonian is derived describing the coexisting phases. The system is characterized by direct and exchange interactions and an external magnetic field. The properties of the system are studied numerically. The stability conditions define the stable state of the system. At a temperature of zero, the system is in a pure ferromagnetic state. However, at finite temperature, for some interaction parameters, the system can exhibit a zeroth-order nucleation transition between the pure ferromagnetic phase and the mixed state with coexisting ferromagnetic and paramagnetic phases. At the nucleation transition, the finite concentration of the paramagnetic phase appears via a jump.

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Coexistence of Nonmagnetic and Magnetic Co in Cubic Laves Phase Compounds Lu(Co_1-xAl_x)₂

Cited by 21 publications

References 10 publications

Itinerant-electron metamagnetism and the onset of ferromagnetism in Laves phase compounds

Itinerant-electron metamagnetism and the onset of ferromagnetism in Laves phase compounds

Itinerant-electron metamagnetism and magneto-volume effects in Lu(Co_1-xAl_x)₂Laves phase compounds

Zeroth-Order Nucleation Transition under Nanoscale Phase Separation

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Coexistence of Nonmagnetic and Magnetic Co in Cubic Laves Phase Compounds Lu(Co1-xAlx)2

Cited by 21 publications

References 10 publications

Itinerant-electron metamagnetism and the onset of ferromagnetism in Laves phase compounds

Itinerant-electron metamagnetism and the onset of ferromagnetism in Laves phase compounds

Itinerant-electron metamagnetism and magneto-volume effects in Lu(Co1-xAlx)2Laves phase compounds

Zeroth-Order Nucleation Transition under Nanoscale Phase Separation

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Product

Resources

About

Coexistence of Nonmagnetic and Magnetic Co in Cubic Laves Phase Compounds Lu(Co_1-xAl_x)₂

Itinerant-electron metamagnetism and magneto-volume effects in Lu(Co_1-xAl_x)₂Laves phase compounds