Competing magnetic interactions driven tuning of spin-flop field and anomalous thermal expansion in MnTi1−xMnxO3.

Autor: Pal, Pratap, Rahaman, Aminur, Brar, Jaskirat, Bindu, R., Choudhury, Debraj
Předmět:
Zdroj: Journal of Applied Physics; 11/14/2022, Vol. 132 Issue 18, p1-7, 7p
Abstrakt: Multiferroic MnTiO3 (MTO) is made up of alternate Mn2+ (3 d 5) and Ti4+ (3 d 0) layers along the c -axis. It undergoes a magnetic spin-flop driven ferroelectric polarization flop beyond ∼ 6 T below T N ∼ 64 K. MTO also exhibits a weak negative thermal expansion along the c -axis below ∼ 90 K. We demonstrate that doping Mn ions at non-magnetic Ti layers acts as a very effective microscopic control parameter to systematically tune both these functional responses. Tuning of c/a lattice parameters in MnTi 1 − x Mn x O3 leads to significant reduction in the spin-flop critical magnetic field from ∼ 6 T to more easily accessible fields (< 2 T for x = 0.05). Simultaneously, the controlled tuning of magnetic frustration due to Mn-doping at Ti sites also helps in a systematic enhancement of anomalous thermal expansion in regard to increasing the onset temperature for anomalous expansion to higher values (by ∼ 40 K for x = 0.10) and also strengthening its magnitude (by ∼ 30 % at 15 K for x = 0.10 in comparison to x = 0.00). Increase in the c/a ratio with Mn doping in MnTiO3 likely causes reduction in the effective magnetocrystalline anisotropy, which leads to a decrease in the value of the spin-flop magnetic field. Detailed temperature-dependent structural analyses shed light on the critical role of exchange striction mechanism in tuning the negative thermal expansion in doped MnTiO3. [ABSTRACT FROM AUTHOR]
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