LuH_(2)反射谱的压力调控

Pressure tuning of optical reflectivity in LuH_(2)

最近,关于近常压条件下Lu-H-N化合物室温超导的报道引发了广泛关注,并迅速引起了学界的讨论和质疑,亟待进一步的研究来重复相关结果和解决争议.这其中一个非常显著的实验现象是样品随加压会呈现由蓝色到粉色再到红色的颜色变化.这一现象在LuH_(2)中得到了复现,但其内在机理仍不清楚.通过可见光到近红外波段的光谱测量,本文在反射谱中观察到了陡峭的等离子边缘,在其能量附近,光被强烈吸收.在常压下,等离子边缘位于725 nm附近,样品对红光强烈吸收,故呈现蓝色.当压力增大时,等离子边缘持续向高能量移动,导致对红光的反射增强,对蓝光的反射减弱,故逐渐转变为红色.从常压到~14 GPa范围内,等离子边缘随压力的移动速度为9.4~12.6 meV/GPa.该工作揭示等离子激元随压力移动的机制对LuH2中观察到的压致变色现象起主导作用,这对理解相关稀土金属氢化物的压力响应提供了线索.

In the last few years,interest in the rare-earth hydrides has been reinvigorated owing to their potentials for hosting room-temperature superconductivity under achievable pressures.Promi-nent examples include LaH10 and YH9,in which the superconduct-ing transition temperature(Tc)approaches 260 K at200 GPa[1–4].Nitrogen(N)doped lutetium hydride was recently claimed to exhibit possible superconductivity at a room temperature of 294 K under near-ambient pressure of1 GPa,concomitant with remarkable color changes from lustrous blue to pink and subse-quently bright red with increasing pressures(a few GPa)[5].