Neutron scattering in magnetic fields: extending the possibilities

There are many materials exhibiting rich variety of magnetic phenomena as a function of magnetic held and temperature. Although bulk magnetization mea surements can provide important information regarding for instance the size of the magnetic moments, anisotropy, etc., there is also a necessity to in vestigate the system on microscopic scale in magnetic fields by means of ne utron scattering. To produce high magnetic fields, pulsed magnets are used which offer at present fields as high as 25 T. However, when magnetic-histo ry phenomena are important, a steady magnetic field has to be generated. Ba sically, it is hard to achieve steady magnetic fields exceeding 12 T mainly due to the necessity to use split-pair coil in order to have free access f or the incoming and scattered neutron beam. Recently, Oxford Instruments ma nufactured for BENSC a symmetrical split-pair 14.5 T superconducting magnet . In this contribution we report on a rather simple method based on Dy-pole tips placed into the split area that provides 2.5 T enhancement leading to a magnetic field of 17 T at the sample position. The temperature range acc essible with such an insert is between 1.8 and 100 K. First experiences and examples of real measurements are presented. (C) 2001 Elsevier Science B.V . All rights reserved.