Neutron Diffraction and muSR studies of the field-dependent magnetic structures and spin dynamics in the double pyrochlore Nd2Ru2O7

Abstract

Nd-pyrochlore compounds host moment fragmentation octupolar order and spin chirality etc novel phenomena Here we report the studies on the double pyrochlore compound of Nd2Ru2O7 using neutron powder diffraction μSR techniques and in-house heat capacity ac susceptibility measurements Polycrystalline Nd2Ru2O7 had been prepared for the studies Heat capacity and magnetic susceptibility measurements on Nd2Ru2O7 reveal three anomalies at 146 21 and 1 8 K corresponding to Ru4+ ordering moment canting and Nd3+ ordering separately The peaks of heat capacity shift and broaden in applied fields gradually motivated us to carry out neutron powder diffraction experiments in applied fields to investigate the variations of magnetic structures The magnetic structure of Nd3+ ion at 50 mK exhibits as an all-in-all-out spin configuration When the fields were applied the magnetic moments had been aligned gradually to a two-in-two-out magnetic structure at high field reminiscent of spin configurations of a classical spin ice The magnetic moment of the Nd3+ ion is estimated as 2 76(7) μB in 9 T in contrast to the moment of 1 54(2) μB in zero field and 400 mK μSR experiments had been employed to study the spin dynamics of Nd2Ru2O7 Wiggling asymmetry spectra which can be fitted by two different oscillation frequencies were observed below the Ru4+ order temperature of 146 K indicating two different magnetic sites where muons are located The transition temperatures determined by μSR are consistent with the neutron and in-house measurements

Date of Award	2021
Original language	English
Supervisor	Lieh-Jeng Chang (Supervisor)