High Pressure experiments in high fields.

The aim of this project is to study magnetically ordered systems in high quasistatic fields (up to 40T) and as a function of temperature (1.5 K up to room temperature). In the existing Austromag system a quasistatic pulse (1s) with fields up to 40 T can be achieved. Already existing parts of this machine (Austromag) as well as the experience and competence in this area will be used. The set up of a pressure cell shall allow experiments under pressure of up to 10 kbar. Using high magnetic fields in combination with high pressure enables to figure out relevant magnetic interactions and parameters, particularly with respect to field induced phase transitions. In order to allow measurements of pressure dependent magnetic properties, the achievable sensitivity for magnetization measurements of the presently used equipment has to be improved. The following work is proposed: 1) Development of a high pressure cell which allows magnetization and magnetoresistence measurements in high quasistatic fields. 2) The magnetization measurement methods has to be improved so that such pressure dependent invstigations become possible. For this purpose a planar pick-up system shall be tested. Additionally a modulation method shall be tried. 3) Tests in high field system. After solving the design and construction problems the whole equipment has to be tested and calibrated. This means in the pressure cell has to be calibrated additionally the magnetization device has also to be tested. 4) Study of field induced phase transitions.Here especially samples which show inverse itinerant electron magnetism are possible canditates. Additionally various REMn2 with H but laso N or C substitutions shall be investigated. 5) Study of high field and pressure dependence of small particle systems. Small particle systems show mainly surface effects. The high field magnetization can be used to detect noncolliniear components of the magnetization. The pressure dependence of the magnetization is one new parameter for superparamagnetic particle systems. 6) Study of pressure dependence of hard magnetic samples and exchange coupled material. Here the hysteresis parameter (mainly the cooercivity) as a function of an external pressure shall be investigated. In exchange coupled systems the pressure effect of the coupling mechanism shall be studied.