Octahedral Distortion and Displacement-Type Ferroelectricity with Switchable Photovoltaic Effect in a 3d^{3}-Electron...

Area of Science:

• Materials Science
• Solid-State Physics
• Crystallography

Background:

• Perovskite oxides with 3d^3 electron configurations typically show limited octahedral distortion.
• Understanding factors that enhance octahedral distortion is crucial for developing new functional materials.

Purpose of the Study:

• To synthesize and characterize a novel perovskite oxide, Hg0.75Pb0.25MnO3 (HPMO), with a 3d^3 Mn^4+ state.
• To investigate the unusual octahedral distortion and ferroelectric properties of HPMO.
• To explore the photovoltaic effects in this material.

Main Methods:

• High-pressure and high-temperature synthesis methods were employed.
• Crystal structure analysis was performed to determine the space group and ionic displacements.
• Spontaneous electric polarization and photocurrent measurements were conducted.

Main Results:

• HPMO, a 3d^3 perovskite, exhibits an octahedral distortion approximately two orders of magnitude larger than typical 3d^3 systems.
• A polar crystal structure (space group Ama2) with significant spontaneous electric polarization was identified.
• Switchable photovoltaic effects and a prominent net photocurrent were observed.

Conclusions:

• HPMO presents an exceptional d^3 material system with large octahedral distortion and displacement-type ferroelectricity, defying the 'd^0-ness' rule.
• The findings offer a new material platform for exploring ferroelectric and photovoltaic functionalities in d^3 perovskites.