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首页> 外文期刊>Physical review >Pressure-driven metal-insulator transition in BiFeO_3 from dynamical mean-field theory
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Pressure-driven metal-insulator transition in BiFeO_3 from dynamical mean-field theory

机译：基于动态均场理论的BiFeO_3中压力驱动的金属-绝缘体转变

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摘要

A metal-insulator transition (MIT) in BiFeO_3 under pressure was investigated by a method combining generalized gradient corrected local density approximation with dynamical mean-field theory (GGA+DMFT). Our paramagnetic calculations are found to be in agreement with the experimental phase diagram: Magnetic and spectral properties of BiFeO_3 at ambient and high pressures were calculated for three experimental crystal structures R3c, Pbnm, and Pm3-barm. At ambient pressure in the R3c phase, an insulating gap of 1.2 eV was obtained in good agreement with its experimental value. Both R3c and Pbnm phases have a metal-insulator transition that occurs simultaneously with a high-spin (HS) to low-spin (LS) transition. The critical pressure for the Pbnm phase is 25-33 GPa, which agrees well with the experimental observations. The high-pressure and -temperature Pm3-barm phase exhibits a metallic behavior observed experimentally as well as in our calculations in the whole range of considered pressures and undergoes the LS state at 33 GPa, where a Pbnm to Pm3-barm transition is experimentally observed. The antiferromagnetic GGA+DMFT calculations carried out for the Pbnm structure result in simultaneous MIT and HS-LS transitions at a critical pressure of 43 GPa in agreement with the experimental data.
机译：通过将广义梯度校正局部密度近似与动态平均场理论（GGA + DMFT）相结合的方法，研究了BiFeO_3在压力下的金属-绝缘体转变（MIT）。我们的顺磁计算与实验相图一致：对于三个实验晶体结构R3c，Pbnm和Pm3-barm，计算了BiFeO_3在环境和高压下的磁性和光谱性质。在R3c相的环境压力下，获得的绝缘间隙为1.2 eV，与实验值高度吻合。 R3c和Pbnm相均具有金属-绝缘体转变，该转变过程与高自旋（HS）到低自旋（LS）转变同时发生。 Pbnm相的临界压力为25-33 GPa，与实验结果吻合良好。高压和高温Pm3-barm相在整个考虑的压力范围内均表现出实验和我们的计算观察到的金属行为，并在33 GPa处经历LS状态，其中实验观察到了Pbnm到Pm3-barm的转变。对Pbnm结构进行的反铁磁GGA + DMFT计算得出，在43 GPa的临界压力下，MIT和HS-LS同时转变，与实验数据一致。

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