Study of Low-Temperature Excitation and Phase Transition in the Frustrated Systems by Nuclear and Electronic Heat Capacities.

通过核和电子热容量研究受抑系统中的低温激励和相变。

基本信息

批准号：
62540268
负责人：
TAKEDA Kazuyoshi
金额：
$ 1.22万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1988
项目状态：
已结题

项目摘要

Information of the ground state and phase transition in frustrated magnetic systems has been obtained by the measurements of nuclear and electronic heat capacity, and magnetic susceptibility.The spin reduction which reflects the magnetic phase at low temperatures is estimated to be 40% for spin s=3/2 of VX_2(X:Br,Cl). This value makes a significant difference when compared with the reduction of 70% obtained from the nuclear diffraction experiment with the time scale of the order 10^<-13> sec.. It is revealed that systematic and dynamical observations are necessary for understanding the ground state of frustrated systems.The linear dependence of the heat capacity on low-temperatures is expected for the Fermi liquid in the resonating valence bond state. The heat capacity of VX_2, however, does not show the T^1 term. The crucial check of this is possible with the frustrated system with s=1/2. Not only the linear dependence of the heat capacity, but also any trace of the phase change is observed in the heat capacity measurements for LiNiO_2: the magnetic susceptibility measurements indicate the possibility of the successive phase transitions at T_<N1>=240K and T_<N2>=15K, which is a feature of the triangular antiferromagnet.In the recent study of the superconductivity, the resonating valence bond state is stressed to play an important role in the CuO_2 plane with the electronic holes. We have begun investigating the resonating valence bond state also in the crystal of organic free radical which has some remarkable points when compared with inorganic compounds with the 3d electron. The magnetic behavior of the unpaired electron system ,triphenylverdazyi, is given as the first example.

通过核和电子热容量的测量以及磁敏感性获得了沮丧磁系统中基态的信息和相变的信息。反映在低温下磁相的自旋降低为VX_2的旋转s = 3/2的磁相为40％（x：x：br，cl）。与从核衍射实验中获得的70％的70％相比，该值与10^<-13> sec的时间尺度相比，这一值有显着差异。.揭示了系统性和动力学观察对于理解挫折系统的基础状态是必要的。预期的是，预期的是，预期的是，对于低血压的线性依赖性对于fermi液体的状态中的效果是在循环字子状态中。但是，VX_2的热容量并未显示T^1项。对于S = 1/2的沮丧系统，可以对此进行关键检查。不仅在linio_2的热容量测量中观察到热容量的线性依赖性，还可以观察到任何相变的痕迹：磁敏感性测量值表明，在T_ <n1> = 240K和T_ <n2> = 15K处连续过渡时的连续相变的可能性，这是统一的porterient andiangular antirogular antirognation ison interant of necoming valsing valsing。强调用电子孔在CUO_2平面中发挥重要作用。我们已经开始研究有机自由基晶体中的共鸣价键态，与3D电子的无机化合物相比，它具有显着的点。未配对电子系统Triphenylverdazyi的磁性行为是第一个例子。