High Magnetic Field X-ray Diffraction at the National High Magnetic Field Laboratory (NHMFL)*

We develop a custom high magnetic field x-ray diffraction system for measurements in the 25 T Florida split coil magnet at the DC Field Facility of NHMFL, Tallahassee, FL, to probe spin-lattice coupling at extreme steady-state magnetic fields. This allows thermal cycling of materials with first order transitions and thermal relaxation of highly conductive or magnetocaloric materials. The system utilizes a Mo rotating anode X-ray source and PILATUS 300K-W X hybrid pixel array detector customized to tolerate the fringe fields of the split coil magnet. We plan to further modify the diffractometer with an elliptical mirror system which will enhance intensity and create a convergent x-ray beam configuration. We present a study of the magnetocaloric material, AlFe₂B₂, highlighting the evolution of the unit cell volume in field and a study of the magnetostrictive material, GdNi, highlighting the evolution of the crystal axes at high field.