Magnetic and magnetotransport properties of intermetallic SmMn2Si2

Abstract

The magnetic properties of naturally layered intermetallic compound SmMn2Si2 with textured structure have been studied. There exist a ferromagnetic transition at 35 K and two antiferromagnetic transitions at 120 and 230 K. The antiferromagnetic state below 230 K exhibits different magnetoresistance, with a negative magnetoresistance of 3%–4% for current I applied perpendicular to the c axis and with a positive magnetoresistance effect of about 4%–6% for current I parallel to the c axis. The observed magnetoresistance is likely to be related to magnetovolume effects. In the ferromagnetic state, a positive magnetoresistance with a maximum increase of 22% under an applied field of 5 T is observed at 4 K, and both H ⊥ I and H ∥ I configurations show positive magnetoresistance.

Anomalous magnetic behavior in Sm(Fe1−Mn )2Si2 system

“…2) corresponds to the phase transition between the low-temperature ferromagnetic phase and the antiferromagnetic phase above 30 K, which in a good agreement with [4]. The small but nonnegligible anomalies at T ∼ 120 and 240 K reflect the order-to-order transitions between two AF phases proposed in [4]. An additional pronounced peak of unknown origin was observed at T = 306 K. In order to demonstrate the pronounced magnetic contribution to the total specific heat of SmMn 2 Si 2 , the C(T) experimental data are compared with the phonon specific heat of paramagnetic LaFe 2 Si 2 in Fig.…”

“…The 'double peak' located around ∼30 K (see Fig. 2) corresponds to the phase transition between the low-temperature ferromagnetic phase and the antiferromagnetic phase above 30 K, which in a good agreement with [4]. The small but nonnegligible anomalies at T ∼ 120 and 240 K reflect the order-to-order transitions between two AF phases proposed in [4].…”

“…The microprobe analysis confirmed the stoichiometry ±3% for all compounds, for SmFe 2 Si 2 an additional Fe-Si phase (ferromagnetic at room temperature) of variable stoichiometry has been detected on grain boundaries. The lattice parameters at 300 K of both border compounds agree well with the literature data [4][5][6]. The lattice parameters and the unit cell volume of pseudoternary samples increase roughly linearly with Mn content.…”

“…Practically no studies have been performed on SmFe 2 Si 2 , for which paramagnetic behavior down to 4.2 K has been reported in [6]. While an antiferromagnetic order of Mn 3d magnetic moments in SmMn 2 Si 2 is expected [4], Fe has been reported to remain nonmagnetic within the entire REFe 2 Si 2 series [7].…”

“…Concerning Sm compounds, much attention has been paid to SmMn 2 Ge 2 , which undergoes several magnetic phase transitions within a wide temperature range and a giant magnetoresistance (GMR) effect [2,3]. For the Si containing compounds, basic studies have been done on SmMn 2 Si 2 reporting an antiferromagnetic (AF) ordering at T N = 398 K, two order-order transitions at 230 and 120 K, respectively, between AF phases and exhibits a ferromagnetic (F) ordering below 35 K as deduced from magnetization data [4,5]. Practically no studies have been performed on SmFe 2 Si 2 , for which paramagnetic behavior down to 4.2 K has been reported in [6].…”