Robust Crystal Phase Separation with Distinct Charge, Orbital, and Spin Orders in AgMn7O12

• Published in: Inorganic chemistry Vol. 63; no. 6; pp. 3191 - 3198
• Main Authors: Lu, Dabiao, Zhang, Jie, Zhao, Haoting, Pi, Maocai, Ye, Xubin, Liu, Zhehong, Wang, Xiao, Zhang, Xueqiang, Pan, Zhao, Hsu, Su-Yang, Chang, Chung-Kai, Chen, Jin-Ming, Hu, Zhiwei, Long, Youwen
• Format: Journal Article
• Language: English
• Published: American Chemical Society 12.02.2024
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.3c04360

An AA′3B4O12-type A-site-ordered quadruple perovskite oxide AgMn7O12 was prepared by high-pressure and high-temperature methods. At room temperature, the compound crystallizes into a cubic Im3̅ symmetry with a charge distribution of AgMn3 3+Mn4 3.5+O12. With the temperature decreasing to T CO,OO ≈ 180 K, the compound undergoes a structural phase transition toward a monoclinic C2/m symmetry, giving rise to a B-site charge- and orbital-ordered AgMn3 3+Mn2 3+Mn2 4+O12 phase. Moreover, this charge-/orbital-ordered main phase coexists with the initial cubic AgMn3 3+Mn4 3.5+O12 phase in the wide temperature range we measured. The charge-/orbital-ordered phase shows two antiferromagnetic phase transitions near 125 and 90 K, respectively. Short-range ferromagnetic correlations are found to occur for the initial B-site mixed cubic phase around 35 K. Because of the robust phase separation, considerable magnetoresistance effects are observed below T CO,OO in AgMn7O12.