Critical phenomena of the layered ferrimagnet Mn3Si2Te6 following proton irradiation

• Published in: Journal of applied physics 2021-07, Vol.130 (1)
• Main Authors: Olmos, Rubyann, Delgado, Jose A., Iturriaga, Hector, Martinez, Luis M., Saiz, Christian L., Shao, L., Liu, Y., Petrovic, C., Singamaneni, Srinivasa R.
• Format: Article
• Language: English
• Subjects: 2D materials; Antiferromagnetism; Applied physics; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Critical phenomena; Entropy; Exponents; Ferrimagnets; Heat exchange; Irradiance; Magnetic anisotropy; Magnetic equipment; Magnetic ordering; Magnetization; Phase transitions; Proton irradiation; Superexchange interactions; Thermodynamic properties; Two dimensional analysis
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/5.0056387

The critical phenomena and magnetic entropy of the quasi-2D ferrimagnetic crystal, Mn3Si2Te6 (MST), is analyzed along the easy axis (H || ab) as a function of proton irradiance. The critical exponents β and γ do not fall into any particular universality class upon proton irradiation. However, for pristine and irradiated samples, the critical exponents lie closer to mean field-like interactions; therefore, long-range interactions are presumed to be sustained in MST. The effective spatial dimensionality reveals that MST remains at d = 3 under proton irradiation, whereas spin dimensionality transitions from an initial n = 1 to n = 2 and n = 3 for 1 × 1015 and 5 × 1015 H+/cm2, indicating XY and Heisenberg interactions, respectively. The spin correlation function reveals an increase in magnetic correlations at 5 × 1015 H+/cm2. Maximum change in magnetic entropy at 3 T is the largest for 5 × 1015 H+/cm2 at 2.45 J/kg K, in comparison to 1.60 J/kg K for pristine MST. These results intriguingly align with previous findings on MST where magnetization increased by ∼50% at 5 × 1015 H+/cm2, in comparison to its pristine counterpart [Martinez et al., Appl. Phys. Lett. 116, 172404 (2020)]. Magnetic entropy derived from heat capacity analysis shows no large deviations across the proton irradiated samples suggesting that the antiferromagnetic (AFM) coupling between the Mn sites is stable even after proton irradiation. This implies that magnetization is enhanced through a strengthening of the super-exchange interaction between Mn atoms mediated through Te rather than a weakening of the AFM component.