论文标题
在2H-NBSE2中的电荷密度波量子相变处没有超导圆顶
Absence of superconducting dome at the charge-density-wave quantum phase transition in 2H-NbSe2
论文作者
论文摘要
超导性通常在量子临界点周围的圆顶中发现，即二阶量子相变。在这里，我们表明，在NBSE $ _2 $中电荷密度（CDW）状态的临界压力下，避免了超导性的增强。我们介绍了nbse $ _2 $中CDW和超导状态的全面的高压大厅效应和磁化率测量。最初，二阶CDW过渡被平稳抑制，但在PCDW = 4.4 GPA时突然下降至零，从而表明将变化为一阶，而超导过渡温度TC则连续上升到PCDW，但在上面是恒定的。 CDW过渡的假定一阶性质被认为是PCDW上没有超导圆顶的原因。确实，我们表明，在低压下对超导状态的抑制是由于CDW相内的状态密度损失所致，而CDW状态的初始抑制是通过基础裸机模式的僵硬来解释的。
Superconductivity is often found in a dome around quantum critical points, i.e. 2nd-order quantum phase transitions. Here, we show that an enhancement of superconductivity is avoided at the critical pressure of the charge-density-wave (CDW) state in NbSe$_2$. We present comprehensive high-pressure Hall effect and magnetic susceptibility measurements of the CDW and superconducting state in NbSe$_2$. Initially, the 2nd-order CDW transition is suppressed smoothly but it drops to zero abruptly at PCDW = 4.4 GPa thus indicating a change to 1st order whilstthe superconducting transition temperature Tc rises continuously up to PCDW but is constant above. The putative 1st-order nature of the CDW transition is suggested as the cause for the absence of a superconducting dome at PCDW. Indeed, we show that the suppression of the superconducting state at low pressures is due to the loss of density of states inside the CDW phase whilst the initial suppression of the CDW state is accounted for by the stiffening of the underlying bare phonon mode.
