Composition and temperature dependence of the thermoelectric power of Ni_2+xMn_1−xGa alloys

Abstract

Abstract. The thermoelectric power (TEP) measurements have been carried out to investigate the changes in the electronic structure associated with the intermartensitic and martensitic transitions in Ni 2+x Mn 1−x Ga (0 ≤ x ≤ 0.19). The samples have been characterized by a.c. magnetic susceptibility measurements. The correlation between the TEP and the microstructural changes sensitive to the increasing Ni content in Ni 2+x Mn 1−x Ga has been investigated. The changes in the density of states as reflected in the temperature variation of the TEP are consistent with the conclusions drawn from the Jahn-Teller mechanism of lattice distortion.

Peek into the World of Materials Using Thermopower and Xafs as Investigative Probes

“…Besides the signatures associated with increasing e/a, and those ascribed to a typical ferromagnetic metal (like TEP minima), we observe almost constant value of TEP over a wide range in temperature in the martensitic phase. This change occurs as a result of nesting vectors formed due to differently modulated crystal structures in the martensitic phase causing weak localization of conduction electrons, as described earlier [6][7] . The highlight of TEP measurements in Ni-Mn-Ga is the slope of TEP that changes quite sharply in going from Ni 2 MnGa to Ni 2.19 Mn 0.81 Ga.…”

Temperature dependence of thermoelectric power and thermal conductivity in ferromagnetic shape memory alloyNi50Mn34In16Chandra1, Chattopadhyay2, Sharma3 et al. 2010Phys. Rev. B28030View full textAdd to dashboardCite

“…[9][10][11] While a considerable amount of experimental results is available in the literature on the magnetic, structural and electrical properties of FSM alloys, 12 there are relatively very few reports on the temperature and magnetic field dependencies of the thermal transport properties. [13][14][15][16][17][18] Thermal transport data on Ni-Mn-Ga FSM alloys show distinct changes across the T C and the MST-AST transitions. [14][15][16][17] Considerable changes in the thermoelectric power ͑Seebeck coefficient͒ are observed in the FSM alloy Ni 50 Mn 36 Sn 14 in presence of magnetic field.…”

“…[13][14][15][16][17][18] Thermal transport data on Ni-Mn-Ga FSM alloys show distinct changes across the T C and the MST-AST transitions. [14][15][16][17] Considerable changes in the thermoelectric power ͑Seebeck coefficient͒ are observed in the FSM alloy Ni 50 Mn 36 Sn 14 in presence of magnetic field. 18 In Ni-Mn-In system, Zhang et al, have reported a considerable change in thermal conductivity of Ni 50 Mn 33.7 In 16.3 alloy in presence of magnetic field.…”

“…2,3,8 The first order nature of this MST-AST transition is responsible for the above said functional properties. 2,3 Recently, we have shown that the MR, MCE, and the magnetic field induced strain in Ni 50 Mn 34 In 16 alloy are dependent on the therno-magnetic history of the sample. [9][10][11] While a considerable amount of experimental results is available in the literature on the magnetic, structural and electrical properties of FSM alloys, 12 there are relatively very few reports on the temperature and magnetic field dependencies of the thermal transport properties.…”

“…18 In Ni-Mn-In system, Zhang et al, have reported a considerable change in thermal conductivity of Ni 50 Mn 33.7 In 16.3 alloy in presence of magnetic field. 13 These results have motivated us to investigate on the temperature dependence of thermal transport properties of Ni 50 Mn 34 In 16 in presence of applied magnetic fields. In the sections below we present a detailed study of the temperature dependence of thermoelectric power ͑S͒ and thermal conductivity ͑͒ in the presence of zero and 20 kOe applied magnetic field.…”