S. Zherlitsyn

New experimental techniques for pulsed magnetic fields – ESR and ultrasonics

Abstract In this paper, we report about our activities to perform ultrasonic and ESR experiments in pulsed fields up to 50xa0T at temperatures down to 1.3xa0K. We describe the ultrasonic technique for the pulsed magnetic field experiments including the details of our setup. We explain how to determine the change of ultrasound velocity Δv/v0 and attenuation α from the experimental data. Our ESR setup together with the details of the sample holders for measurements in Faraday and Voigt geometry is given.

Elastic properties of ferromagnetic EuB6

Abstract:Results of an ultrasonic investigation of EuB6 at low temperatures are reported. Both longitudinal and transverse acoustic modes exhibit anomalies in the vicinity of the low-temperature phase transitions of EuB6. The ultrasound data serve to establish part of the B-T phase diagram of EuB6. At magnetic fields exceeding 3 T, magneto-acoustic quantum oscillations (MAQO) are observed. The nature of the acoustic anomalies and possible phases in external magnetic fields are discussed. Also a comparison with the elastic properties of other rare-earth (RE) hexaboride compounds is made.

Pulsed field ultrasonic and ESR experiments in low-dimensional spin systems

Abstract We present the ultrasonic and ESR results for several low-dimensional spin systems in high magnetic fields up to 50xa0T. With these experiments, we obtain information on the spin state in high fields, their magnetic excitations and on the interaction of these magnetic excitations with phonons. The deduced spin–phonon coupling constant gives information on the structural properties and their connection to low-dimensional magnetism of the systems.

High-field ultrasonics in the heavy fermion antiferromagnet URu2Si2

Abstract In the antiferromagnetic heavy fermion superconductor URu 2 Si 2 we observe the spin flop transition around 39xa0T below the Neel temperature T N using longitudinal sound. The c 33 -mode exhibits only one-step like anomaly at the spin flop transition in contrast to the three steps found in magnetization, magnetoresistance measurements and the longitudinal c 11 mode. This behaviour can be explained using the Gruneisen parameter coupling for the field dependence of the elastic constants. Above the Neel temperature of 17.5xa0K we find a softening of the c 33 elastic constants in high magnetic fields.

Ultrasonic experiments in SrCu2(BO3)2 and NH4CuCl3 in magnetic fields up to 50 T

Abstract We present sound velocity data in high fields for the two plateau substances SrCu 2 (BO 3 ) 2 and NH 4 CuCl 3 . Pronounced sound velocity and attenuation anomalies are observed in the region between the magnetization plateaus. We interpret these as a resonant interaction between the sound wave mode and the soft magnetic excitations.