Impacts of pressure to the structural, electronic and magnetic properties of Dirac semimetal EuMnBi_{2}

We report our investigations on the effects of pressure on the electronic and magnetic properties of magnetic Dirac semimetal EuMnBi_{2} by using electrical transport, synchrotron x-ray diffraction, and x-ray absorption spectroscopy. The antiferromagnetic interaction due to the Eu magnetic moment in EuMnBi_{2} is enhanced under pressure up to ∼3.9GPa. The Néel temperature (T_{N}) is found to disappear above 4 GPa and a new transition T_{t} at around 29 K emerges above 6 GPa. T_{t} remains relatively constant up to 15 GPa, above which it increases with further compression, reaching ∼60K at 22 GPa. Eu L-edge x-ray absorption spectroscopy revealed a valence change of Eu toward a trivalent state that begins above 6 GPa, which indicates that T_{t} is likely related to the valence transition temperature of Eu. Sign reversal of the Hall resistivity above 7 GPa suggests that the valence change of Eu also induces a Fermi surface modification.