Nie Shouhua, Wang Xuan, Park Hyuk, Clinite Richard, Cao Jianming
Physics Department and National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
Phys Rev Lett. 2006 Jan 20;96(2):025901. doi: 10.1103/PhysRevLett.96.025901. Epub 2006 Jan 19.
We report the first accurate measurement of the electronic Grüneisen constant gamma(e) using a novel method employing the new technique of femtosecond electron diffraction. The contributions of the conduction electrons and the lattice to thermal expansion are differentiated in the time domain through transiently heating the electronic temperature well above that of the lattice with femtosecond optical pulses. By directly probing the associated thermal expansion dynamics in real time using femtosecond electron diffraction, we are able to separate the contributions of hot electrons from that of lattice heating, and make an accurate measurement of gamma(e) of aluminum at room temperature. This new approach opens the possibility of distinguishing electronic from magnetic contributions to thermal expansion in magnetic materials at low temperature.
我们报告了首次使用一种采用飞秒电子衍射新技术的新颖方法对电子格林艾森常数γ(e)进行的精确测量。通过用飞秒光脉冲将电子温度瞬态加热到远高于晶格温度，在时域中区分了传导电子和晶格对热膨胀的贡献。通过使用飞秒电子衍射实时直接探测相关的热膨胀动力学，我们能够将热电子的贡献与晶格加热的贡献区分开来，并在室温下对铝的γ(e)进行精确测量。这种新方法为在低温下区分磁性材料中电子和磁性对热膨胀的贡献开辟了可能性。
