Pregelj Matej, Guguchia Zurab, de Weerd Marie-Cécile, Boulet Pascal, Vrtnik Stanislav, Dolinšek Janez
J. Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia.
Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000, Ljubljana, Slovenia.
Sci Rep. 2022 Aug 1;12(1):13184. doi: 10.1038/s41598-022-17298-6.
We report on the dynamics of a magnetic-field-driven antiferromagnetic-to-paramagnetic quantum phase transition in monocrystalline CeAl via transverse-field muon spin rotation (TF-µSR) experiments down to low temperature of [Formula: see text] 80 mK. The quantum phase transition is of a spin-flip type and takes place on the Ce-Al magnetic chains as a result of competition between the indirect exchange and the Zeeman interaction of the Ce moments with the external field, applied along the chain direction (also the direction of the antiferromagnetic axis). The Ce moments are not static at [Formula: see text] 0, but fluctuate in their direction due to the Heisenberg uncertainty principle. Upon applying the magnetic field sweep, the fluctuations exhibit the largest amplitude at the quantum critical point, manifested in a maximum of the muon transverse relaxation rate at the critical field. The quantum nature of fluctuations observed in the TF-µSR experiments is reflected in the temperature independence of the average local magnetic field component along the external magnetic field at the muon stopping site(s) and the muon transverse relaxation rate within the investigated temperature range 1.5 K-80 mK. Quantum fluctuations are fast on the muon Larmor frequency scale, [Formula: see text] 10 s.
我们通过低至80 mK的低温下的横向场μ子自旋旋转（TF-µSR）实验，报道了单晶CeAl中磁场驱动的反铁磁到顺磁量子相变的动力学。该量子相变属于自旋翻转类型，发生在Ce-Al磁链上，这是由于Ce磁矩与沿链方向（也是反铁磁轴方向）施加的外场之间的间接交换和塞曼相互作用相互竞争的结果。在T = 0时，Ce磁矩并非静止不动，而是由于海森堡不确定性原理在方向上发生波动。施加磁场扫描时，涨落在量子临界点处表现出最大幅度，表现为临界场处μ子横向弛豫率达到最大值。在TF-µSR实验中观察到的涨落的量子特性体现在μ子停止位置处沿外磁场方向的平均局部磁场分量以及所研究温度范围1.5 K - 80 mK内的μ子横向弛豫率与温度无关。量子涨落在μ子拉莫尔频率尺度上很快，约为10 s⁻¹ 。
