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arXiv 1502.04948cond-mat.str-el
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压力作用下UGa2磁性的变化

Variations of magnetic properties of UGa2 under pressure

A. V. Kolomiets, J. -C. Griveau, J. Prchal, A. V. Andreev, L. Havela

摘要:

研究了5 f铁磁体UGa 2单晶样品的电阻率ρ(T)随压力和磁场的变化。居里温度从准静水压力下的T $_{C}$ = 124 K单调上升到p = 14.2 GPa时的154 K,之后急剧下降,在p = 15.2 GPa时达到T $_{C}$ = 147 K。在20 GPa下,化合物已经是非磁性的。这种戏剧性的变化是兼容的交换相互作用介导的5 f杂交与非f状态。外部压力首先增强了5 f矩的交换耦合,但最终通过冲洗5 f矩而抑制了顺序。这样的两带模型对于弱离域的5 f态是足够的。产生非常高的ρ值(300 μΩ.cm)的自旋无序电阻率逐渐被压力抑制。在顺磁状态下,这导致从初始负dρ/dT到正dρ/dT的交叉。

英文摘要:

Electrical resistivity ρ(T) of the 5f ferromagnet UGa2 was investigated for single-crystal samples as a function of pressure and magnetic field. The Curie temperature monotonously increases from T$_{C}$ = 124 K under quasi-hydrostatic pressure up to 154 K at p = 14.2 GPa, after which it turns down steeply and reaches T$_{C}$ = 147 K at p = 15.2 GPa. At 20 GPa the compound is already non-magnetic. This dramatic variation is compatible with exchange interactions mediated by the 5f hybridization with the non-f states. The external pressure first enhances the exchange coupling of the 5f moments, but eventually suppresses the order by washing out the 5f moments. Such a two-band model is adequate for the weakly delocalized 5f states. The spin-disorder resistivity, which produces very high ρ-values (300 μΩ.cm) is gradually suppressed by the pressure. In the paramagnetic state, this leads to a crossover from initial negative to positive dρ/dT.

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