低温高压极端条件下空穴掺杂T“相铜氧化和物物性研究

The T′- R2CuO4 cuprate is the parents phase of the electron-doped ightemperature superconductors, which exhibite many differences from the moreextensively studied hole-doped high-Tc cuprates in both its normal state andsuperconducting properties. This system also exhibites a variety of interestingmagnetic behaviors involving both the rare-earth and copper spin. It is a very goodsystem to study the relation between the magnetic behavior of parents phase and itssuperconducting phase. Under the support of this fund, we have systematicallyinvestigated a new low temperature abnormal magnetic transition of T′-R2CuO4synthesized under high oxygen pressure at about 28 K which was first found byourself. The results show the magnetic anomaly is a common intrinsic behavior ofT′-structure by high pressure, due to the ferromagnetic clusters on CuO2 planes byoxygen doping. The results also imply that the apical oxygen plays a very importantrole in hole doping process onto CuO2 planes, and determined many different.properties between n-type and p-type high-Tc cuprates. It will be very difficult todope the T′-structure to superconduct by hole –doping. For the CuO2 plane of thehigh pressure oxygen doped T′-R2CuO4 is a very lightly hole doped system, it givesa very usefull carrier to study the relation between doped hole and the AF momentof the copper oxides. In addition to these, we found a insulator-metal transition inT’-structure by Se dopping. An easy to use and the pressure can reach as high as 10Gpa high-pressure appratuse which can use at low temperture for transportproperties measurement is set up during research activity.

弄清掺杂载流子与铜氧面反铁磁序之间的相互关系是理解高温超导电性的关键。本项目拟采用高温高压合成方法对T"相化合物进行空穴掺杂，并在已首先发现的由稀掺杂空穴形成的低温磁相基础上，利用常规物性测试手段和低温高压极端条件，进一步研究该稀掺杂系统中丰富的磁行为，及稀土离子磁性、晶体结构和畸变的影响，寻找超导电子的配对信息。