论文标题
在EUPD $ _2 $（SI $ _ {1-X} $ GE $ _X $）$ _ 2 $使用He-Gas压力
From magnetic order to valence-change crossover in EuPd$_2$(Si$_{1-x}$Ge$_x$)$_2$ using He-gas pressure
论文作者
论文摘要
We present results of magnetic susceptibility and thermal expansion measurements performed on high-quality single crystals of EuPd$_2$(Si$_{1-x}$Ge$_x$)$_2$ for 0 $\leq$ x $\leq$ 0.2 and temperatures 2 K $\leq T \leq$ 300 K. Data were taken at ambient pressure and finite He-gas pressure $p$ $ \ LEQ $ 0.5 GPA。对于X = 0和环境压力，我们观察到一个明显的价值交叉，以$ t'_v $ $ \ $ \ $ 160 k为中心，并具有非磁基状态。这种变化 - 变化的跨界特征的特征是d $ t'_v $ /d $ p $ =（80 $ \ pm 10）$ k /gpa的压力依赖性非常强。我们观察到$ t'_v $的转移向降低温度，GE浓度增加，达到$ t'_v $ \ $ \ $ \ $ 90 k的x = 0.1，同时仍显示出非磁基状态。值得注意的是，在进一步将x增加到0.2时，我们发现稳定的欧盟$^{（2+δ）+} $价值，远程反铁磁序以下$ t_n $ =（47.5 $ \ pm 0.1）k，反映了该系统中两个能量尺度之间的紧密竞争。实际上，通过施加高达0.1 GPA的静水压力，该系统的基态可以从$ p $ $ <0.1 $ <$ <$ <$ <$ p $ p $ $ $ $ \ geq $ 0.1 $ 0.1 gpa的远程反铁磁订单更改为中等价值状态。
We present results of magnetic susceptibility and thermal expansion measurements performed on high-quality single crystals of EuPd$_2$(Si$_{1-x}$Ge$_x$)$_2$ for 0 $\leq$ x $\leq$ 0.2 and temperatures 2 K $\leq T \leq$ 300 K. Data were taken at ambient pressure and finite He-gas pressure $p$ $\leq$ 0.5 GPa. For x = 0 and ambient pressure we observe a pronounced valence-change crossover centred around $T'_V$ $\approx$ 160 K with a non-magnetic ground state. This valence-change crossover is characterized by an extraordinarily strong pressure dependence of d$T'_V$ /d$p$ = (80 $\pm 10)$ K/GPa. We observe a shift of $T'_V$ to lower temperatures with increasing Ge-concentration, reaching $T'_V$ $\approx$ 90 K for x = 0.1, while still showing a non-magnetic ground state. Remarkably, on further increasing x to 0.2 we find a stable Eu$^{(2+δ)+}$ valence with long-range antiferromagnetic order below $T_N$ = (47.5 $\pm$ 0.1) K, reflecting a close competition between two energy scales in this system. In fact, by the application of hydrostatic pressure as small as 0.1 GPa, the ground state of this system can be changed from long-range antiferromagnetic order for $p$ $<$ 0.1 GPa to an intermediate-valence state for $p$ $\geq$ 0.1 GPa.
