A magnetic x-ray diffraction investigation of gadolinium selenide

A single-crystal synchrotron radiation study of gadolinium selenide has been made in the temperature range 15 - 100 K. GdSe has the rocksalt structure and becomes antiferromagnetic below a reported Neel temperature of 65 K. At 15 K, magnetic reflections are observed at with modulation wavevector propagating from reciprocal lattice point G. This is achieved by exploiting the resonant enhancement in the vicinity of the and edges. Similar enhancements are observed at the two edges, with the maximum effect occurring approximately 3 eV above the absorption edge. The temperature dependence of the intensity of the magnetic reflections indicates a Neel temperature of 63(1) K. These measurements, together with high-resolution studies of the fundamental reflections , contribute further evidence of magnetic or structural changes in the sample at 37(1) K. Our observations are discussed and compared with previous x-ray diffraction and magnetic susceptibility measurements.