Large exchange bias and magnetocaloric effect in TbMn2Si2

Abstract

We report multiple first order magnetic transitions in TbMn2Si2 as evidenced by the thermal hysteresis in the M-T data and the Arrott plots. Metamagnetic transitions are observed at various temperatures as a result of the antiferromagnetic to ferromagnetic transition of the Mn sublattice. Very interestingly, the compound shows significant exchange bias field of about 600 Oe at 5 K, which is attributed to the formation of small domains or regions with ferromagnetic and antiferromagnetic interactions. Furthermore, a large magnetocaloric effect has been found at relatively low fields at both the transition regions. Maximum magnetic entropy changes (−ΔSM) of 7.2 and 5.4 J kg−1 K−1 have been observed at 68 K and at 48 K, respectively, at 20 kOe.

Large entropy change accompanying two successive magnetic phase transitions in TbMn2Si2 for magnetic refrigeration

“…By comparison, a recent work on TbMn 2 Si 2 also reported similar transitions but with slightly different values of T c1 (46 K) and T c2 (68 K). 18 This was attributed to the nonstoichiometric ratio caused by uncontrollable loss of manganese.…”

“…The S-shaped nature of the Arrott plot near T c2 denotes the negative sign of the coefficient c 2 (T) in the Landau expansion of the magnetic free energy, confirming the characteristic of a first order magnetic transition. 18 The ÀDS M of the sample was calculated from the magnetization isotherm curves in Figure 3(a) using an integral version of Maxwell's thermodynamic relation…”

“…25,26 It displays the classical first order phase transition, and has two phase transition temperatures located at about 50 and 70 K. Two adjacent magnetic phase transitions may make this material display large ÀDS M /DT ad over a wide temperature range, although there have been only a few reports on the MCE in TbMn 2 Si 2 . 18 In order to achieve a complete understanding of TbMn 2 Si 2 , in this paper, we studied the magnetic properties of this compound, especially its MCE property using variable temperature X-ray diffraction, together with magnetic and specific heat measurements.…”

“…A number of magnetic materials with large values of DS M /DT ad accompanied by a first order phase transition have been reported. [9][10][11][12][13][14][15] Nevertheless, only some of them, especially rare-earth-based intermetallic compounds, [16][17][18][19][20][21] have a small hysteresis loss, which is desirable for practical application. In addition, large reversible MCEs only appear in a small temperature range for most of the rare-earth-based intermetallic compounds.…”

Size dependent magnetic and electrical properties of Ba-doped nanocrystalline BiFeO3

“…o C with applied fields in the range of 5 to 8 kOe which is attributed to the magnetic field induced AFM to FM metamagnetic transition 46 in this nanoparticle system. This behavior also demonstrates the presence of mixed magnetic phases.…”