论文标题
限制核自旋的磁量子关键性
Limits to magnetic quantum criticality from nuclear spins
论文作者
论文摘要
量子相变的现象学涉及在低温和能量下的物理，相应的固态实验通常达到millikelvin温度。但是，在许多固体中，核自旋的影响及其超细相互作用不再可以忽略不计。这可能会限制电子量子关键现象的可观察性。在这里，我们讨论了连续磁量子相变的影响，如何通过耦合到核自旋的影响，修改或破坏。我们使用简单但范式的自旋模型来实现磁量子关键性，并确定由于存在核自旋而导致的相图，激发光谱和热力学的修改。我们估计了跨界量表，其中纯粹的电子量子关键性不再可观察到，并讨论在低温下出现的新型物理学。我们的结果与显示磁量子相变的各种化合物有关，更普遍地突出了量子关键系统对小扰动的敏感性。
The phenomenology of quantum phase transitions concerns physics at low temperatures and energies, and corresponding solid-state experiments often reach millikelvin temperatures. However, this is a scale where in many solids the influence of nuclear spins and their hyperfine interaction is no longer negligible. This may limit the observability of electronic quantum critical phenomena. Here we discuss how continuous magnetic quantum phase transitions get influenced, modified, or destroyed by the coupling to nuclear spins. We use simple yet paradigmatic spin models for magnetic quantum criticality and determine modifications to the phase diagram, the excitation spectrum, and thermodynamics due to the presence of nuclear spins. We estimate crossover scales below which purely electronic quantum criticality is no longer observable, and discuss the novel physics emerging at low temperatures. Our results are relevant for a variety of compounds displaying magnetic quantum phase transitions and, more generally, highlight the sensitivity of quantum critical systems to small perturbations.
