Fig.1: High-field M(H) curves at T= 1.6 K for (a) Ni2-xZnxV2O7 and (b) Ni2-xMnxV2O7 samples. For a better version, the curves in (a), (b) have been shifted vertically, and the well-defined magnetization plateau between Hc1 and Hc2 is presented clearly. DP as a function of H measured at various temperatures under the magnetic field up to 58 T. For the Zn doping: (c)x= 0.2; Mn doping: (d)x= 0.1. The arrows denote the field-rising (-falling) sweeps. Prior to measurements, the sample is cooled down to target temperatures under a poling electric field, and then maintained during the short pulse to completely polarize ferroelectric domains. For clarity, the curves have been moved vertically. (e) Field-dopant concentration (H-x) phase diagram is summarized for Ni2-xZnxV2O7 and Ni2-xMnxV2O7 samples, based on the result of high-field magnetizations (solid dots and triangles) and electric polarizations (stars). The yellow (light blue) area represents the half quantum magnetization plateau for Zn- (Mn-) doped cases.
Background
Low-dimensional frustrated magnetic materials exhibit abundant physical effects under the magnetic field, such as fractional magnetization plateaus,magnetically induced ferroelectricities. The former describes a quantum state that the magnetization (M) is magnetic field (H)-independent in a finite field range and its value is a fraction of saturation magnetization (Ms). The latter refers to a phase where two or more ferroic orders such as antiferromagnetism and ferroelectricity coexist.Above two effects have the strict requirement for spin configurations of the material itself, so it is difficult to observe and study them simultaneously in a single material. Recently, as a newly discovered multiferroics R2V2O7(R= Ni, Co), they have attracted much attentions due to showing a fractional magnetization plateau under high magnetic fields.However, until now, there has been little evidence that the magnetization plateau and ferroelectricity of R2V2O7(R= Ni, Co) are simultaneously tuned in some ways.
What we discover?
In this work, we report an efficient approach with chemical substitutions to achieve flexible control of a half quantum magnetization plateau and high-field ferroelectricity in the S= 1 skew-chain antiferromagnet Ni2V2O7. In Zn-doped cases, the half quantum magnetization plateau is remarkably broadened with an increasing concentration on dopants, such as a giant variation reaching 70% at x= 0.7. In contrast, the width of magnetization plateaus for Mn-doped samples pronouncedly shrinks about −37.4% at x= 0.2. Intriguingly, we find that the end of half magnetization plateaus locates in the same position between two groups of samples. In particular, the nontrivial magnetoelectric coupling related with the high-field ferroelectricity performs an identical evolution for Ni2-xTxV2O7(T= Zn or Mn) by sweeping magnetic fields. As a consequence, a close correlation between the half magnetization plateau and ferroelectricity is confirmed, indicating that the high-field polarization is derived from peculiar magnetic moments in Ni2V2O7. Possible origins for the Zn- and Mn-doping effects on the quantum magnetization plateau and multiferroicity are discussed. In addition, high-field phase diagrams with the plateau and ferroelectricity are constructed for these doped compounds.
Why is this important?
The synchronized observation of a fractional magnetization plateau and multiferroicity is of particular interest in frustrated antiferromagnets, but the modulation of two different fascinating phenomena is greatly challenging and urgently desired. Our experimental findings open an additional avenue to tune the quantum magnetization plateau and magnetically induced ferroelectricity, simultaneously. It also provides a chemical doping approach to modulate and study these layering effects under low temperatures and high magnetic fields.
Who did the research?
Tian Li1, Haowen Wang1,2,*, Yiru Song1, Chao Dong1, Rui Chen3, Ming Yang1, and Junfeng Wang1
(1) Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
(2) Department of Applied Physics, School of Science, Wuhan University of Science and Technology, Wuhan 430081, China
(3) College of Physics and Electronic Engineering, Xinyang Normal University, Xinyang 464000, China
Physical Review B 108, 224414 (2023)
https://journals.aps.org/prb/abstract/10.1103/PhysRevB.108.224414
Funding
This work was supported by the National Natural Science Foundation of China (Grants No. 12104351, No. 12074135, and No. 12104388), the Hubei Province Natural Science Foundation of China (Grant No. 2021CFB027), and the China Postdoctoral Science Foundation (Grant No. 2023M731209).
