Koc A, Reinhardt M, von Reppert A, Rössle M, Leitenberger W, Gleich M, Weinelt M, Zamponi F, Bargheer M
Helmholtz Zentrum Berlin, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
J Phys Condens Matter. 2017 Jul 5;29(26):264001. doi: 10.1088/1361-648X/aa7187.
We study gadolinium thin films as a model system for ferromagnets with negative thermal expansion. Ultrashort laser pulses heat up the electronic subsystem and we follow the transient strain via ultrafast x-ray diffraction. In terms of a simple Grueneisen approach, the strain is decomposed into two contributions proportional to the thermal energy of spin and phonon subsystems. Our analysis reveals that upon femtosecond laser excitation, phonons and spins can be driven out of thermal equilibrium for several nanoseconds.
我们研究钆薄膜，将其作为具有负热膨胀特性的铁磁体的模型系统。超短激光脉冲使电子子系统升温，我们通过超快X射线衍射跟踪瞬态应变。根据一种简单的格林艾森方法，应变被分解为与自旋和声子子系统的热能成正比的两种贡献。我们的分析表明，在飞秒激光激发下，声子和自旋能够在几纳秒内偏离热平衡状态。
