Quest for the high-field phase of CdCr₂O₄ using an X-ray diffraction technique

Single-crystal x-ray diffraction experiments on the geometrically frustrated magnet CdCr₂O₄ have been carried out under pulsed magnetic fields up to 31 T. By applying magnetic fields, CdCr ₂O₄ exhibits a magnetization plateau which is one-half of the saturated magnetization above 28 T, and it is expected that a structural transition from a tetragonal to a rhombohedral or cubic structure occurs simultaneously through a so-called "spin Jahn-Teller" mechanism. Our diffraction experiments confirmed that a sharp structural transition occurs at 28 T and that the 440 reflection is a single peak, suggesting that the crystal structure of the high-field plateau phase is cubic.