Field-induced quantum phase transitions studied by means of low-temperature magnetization, specific heat and dielectric measurements

量子相变是零温度下物质的不同相之间的相变。与通常的经典相变可以通过降低温度来实现相反，量子相变只能通过在绝对零温下改变控制参数如磁场、压力或化学成分来实现。量子相变由于描述了由于量子涨落引起的多体系统基态的突变以及可能出现的奇异相而引起了人们的极大关注。在本项目中，我们对各种磁场诱导的量子相变进行了实验研究。为此，我们开发了一种低温磁强计，其工作温度可低至50MK，磁场最高可达17T--这是一项最先进的技术。

A quantum phase transition is a transition between different phases of matter at zero temperature. Contrary to the ordinary classical phase transitions which can be attained by decreasing temperature, quantum phase transitions can only be accessed by varying a controlling parameter such as magnetic field, pressure or chemical compositions at absolute zero temperature. Quantum phase transitions have attracted much attention because they describe abrupt changes in the ground state of many-body systems due to quantum fluctuations and exotic phases may appear. In this project, various magnetic-field-induced quantum phase transitions have been studied experimentally. For this purpose, we have developed a low-temperature magnetometer operating at low temperatures down to 50 mK in magnetic fields up to 17 T-a state of the art technology.