Realization of Intrinsic Colossal Magnetoresistance in Pb(Pb<sub>1/3</sub>Hg<sub>2/3</sub>)<sub>3</sub>Mn<sub>4</sub>O<sub>12</sub>: An A Site-Ordered Quadruple Perovskite Oxide
Jie Zhang, Xubin Ye, Xiao Wang, Zhao Pan, Maocai Pi, Shuai Tang, Dong Cheng, Chien‐Te Chen, Jin‐Ming Chen, Chang‐Yang Kuo, Zhiwei Hu, Xi Shen, Xiaohui Yu, Yao Shen, Richeng Yu, Youwen Long
Abstract
Colossal magnetoresistance (CMR) effects have been extensively studied in ABO 3 perovskite manganites where the Mn 3+ –O–Mn 4+ double-exchange mechanism plays a pivotal role. However, A-site-ordered AA′ 3 B 4 O 12 -type quadruple perovskite oxides exhibit significantly suppressed double exchange due to their extremely small B–O–B bond angles (≈140°), hindering the realization of intrinsic CMR effects. Here, we report the design and synthesis of a novel quadruple perovskite oxide Pb(Pb 1/3 Hg 2/3 ) 3 Mn 4 O 12 (PPHMO) characterized by an unusually increased Mn–O–Mn bond angle of up to 153°. This compound crystallizes into a cubic Im 3̅ structure with the charge distribution Pb 2+ (Pb 1/3 3.5+ Hg 2/3 2+ ) 3 Mn 4 3.63+ O 12 . A ferromagnetic phase transition is observed at the Curie temperature T C ≈ 120 K, accompanied by an insulator-to-metal transition. Furthermore, applying magnetic fields significantly reduces the resistivity, resulting in intrinsic CMR effects with an absolute MR value of 650% at 8 T, increasing to 2250% at 16 T near T C . The large intrinsic MR is thereby realized unprecedentedly in an A-site-ordered quadruple perovskite oxide. Related origins for the intrinsic CMR effects presented in the current PPHMO are discussed in detail.