Quantum Griffiths singularity (QGS) reveals the profound influence of quenched disorder on the quantum phase transitions, characterized by the divergence of the dynamical critical exponent at the boundary of the vortex glasslike phase, named as quantum Griffiths phase. However, in the absence of vortices, whether the QGS can exist under a parallel magnetic field remains a puzzle. Here, we study the magnetic field induced superconductor–metal transition in ultrathin crystalline ${\mathrm{PdTe}}_2$ films grown by molecular beam epitaxy. Remarkably, the QGS emerges under both perpendicular and parallel magnetic field in four-monolayer ${\mathrm{PdTe}}_2$ films. The direct activated scaling analysis with a new irrelevant correction has been proposed, providing important evidence of QGS. With increasing film thickness to six monolayers, the QGS disappears under perpendicular field but persists under parallel field, and this discordance may originate from the differences in microscopic processes. Our work demonstrates the universality of parallel field induced QGS and can stimulate further investigations on novel quantum phase transitions under parallel magnetic field.

中文翻译：

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二维晶体超导体平面内量子格里菲斯奇点的观察

量子格里菲斯奇点 (QGS) 揭示了淬灭无序对量子相变的深远影响，其特征在于涡旋玻璃状相边界处的动力学临界指数的发散，称为量子格里菲斯相。然而，在没有涡流的情况下，QGS能否在平行磁场下存在仍然是一个谜。在这里，我们研究了超薄晶体中磁场诱导的超导体-金属转变${\mathrm{PdTe}}_2$通过分子束外延生长的薄膜。值得注意的是，QGS 在四单层的垂直和平行磁场下出现${\mathrm{PdTe}}_2$电影。提出了具有新的无关校正的直接激活缩放分析，为 QGS 提供了重要证据。随着薄膜厚度增加到六个单层，QGS在垂直场下消失但在平行场下持续存在，这种不一致可能源于微观过程的差异。我们的工作证明了平行场诱导 QGS 的普遍性，并可以激发对平行磁场下新型量子相变的进一步研究。