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

量子相变是物质在零温度下的不同相之间的转变。与可以通过降低温度来实现的普通经典相变相反，量子相变只能通过改变控制参数（如磁场、压力或化学成分）来实现。量子相变描述了由于量子涨落引起的多体系统基态的突变，并且可能出现奇异相，因此引起了人们的广泛关注。本课题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力计，在高达17 t的磁场中，在低至50 mK的低温下工作，这是最先进的技术。

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.