Abstract
Co4Nb2O9 (CNO) is one of the interesting magnetoelectric materials. Here, we report comprehensive temperature-dependent structural, phonon, dielectric, and magnetic properties of CNO. In contrast to most of the earlier reports, a clear transition (upturn feature) is observed in temperature-dependent dielectric measurements at the antiferromagnetic ordering (TN) ∼27.2 K, even in the absence of magnetic field. The upturn-like feature at TN (in zero magnetic field) becomes a sharp peak above the critical magnetic field. The isothermal magnetodielectric (MD) results infer magnetic field-induced transition below TN with nonlinear behavior. The maximum MD effect (∼4%) is observed at TN at 80 kOe. The terahertz measurements exhibit spin excitation mode below TN in the absence of magnetic field. The temperature-dependent synchrotron X-ray diffraction results demonstrate that the crystal structure of CNO remained P3¯ c1 down to 12 K; however, small distortion in the lattice is observed at TN. The temperature-dependent Raman measurements infer an unusual phonon shift and line width of optical phonons below TN. These results illustrate that CNO exhibits dielectric transition even in the absence of magnetic field and exhibit magnetoelastic coupling. The correlation in these order parameters is also discussed.
| Original language | English |
|---|---|
| Pages (from-to) | 14986-14994 |
| Number of pages | 9 |
| Journal | Journal of Physical Chemistry C |
| Volume | 126 |
| Issue number | 35 |
| DOIs | |
| State | Published - Sep 8 2022 |
| Externally published | Yes |
Funding
S.Y. is thankful to Director Prof. A.K. Pal and Center Director Dr. V. Sathe of UGC-DAE-CSR, Indore for their encouragement and financial support during the COVID-19 pandemic. K.S. would like to thank UGC-DAE CSR Indore for providing the financial support under CSR project (CSR-IC-ISUM-26/CSR-309/2019-20/1361). K.S. also thanks the Science and Engineering Research Board (SERB), Department of Science and Technology, New Delhi, for financial support under Core Research Grant Project No. CRG/2021/007075. K.S. and S.Y. would like to thank Dr. Arvind Kumar Yogi for fruitful discussion regarding the magnetic structure of the system, Mr. M. N. Singh for temperature-dependent SXRD measurements and Mr. Ajay Kumar Rathore for the help in temperature-dependent Raman measurements. We would like to thank Dr. M. K. Chattopadhyay for his interest and support for the THz optical studies.