Magnetic-Field Induced Phase Transitions in a Weakly Coupleds=1/2Quantum Spin Dimer SystemBa3Cr2O8

Abstract

By using bulk magnetization, electron spin resonance (ESR), heat capacity, and neutron scattering techniques, we characterize the thermodynamic and quantum phase diagrams of ${\mathrm{Ba}}_3{\mathrm{Cr}}_2{\mathrm{O}}_8$. Our ESR measurements indicate that the low field paramagnetic ground state is a mixed state of the singlet and the $S_z=0$ triplet for $H\perp c$. This suggests the presence of an intradimer Dzyaloshinsky-Moriya (DM) interaction with a DM vector perpendicular to the $c$ axis.