Resistivity and Tunnel Magnetoresistance in Double‐Perovskite Strontium Ferromolybdate Ceramics

Abstract

The low‐field magnetoresistance properties in double‐perovskite strontium ferromolybdate core–shell structures arise from spin‐dependent tunneling through a barrier formed by the shell. It is strongly dependent on synthesis conditions. In this work, first, the resistivity behavior of granular strontium ferromolybdate ceramics comprising intergrain tunnel barriers is reviewed. Based on this generalization, the modification of the tunneling process with barrier thickness and interface conditions is demonstrated. For the first time, equations for the magnetoresistance in each special case are derived.

The Origin of the Low-Temperature Minimum of Electrical Resistivity in Strontium Ferromolybdate Ceramics

“…On the other hand, this contradicts the data derived from [29], where T 1 /T 0 increases with magnetic flux. For metallic conductivity, the values of R m and m in Equation ( 8) are correlated [77]. In our case, this is illustrated in Figure 4, showing an exponential decrease in R m with m. Note that Figure 4 yields for m = 1.5 a value of ρ 1.5 ≈ 3 × 10 −6 ΩmK −3/2 which is required in Equation (3).…”

“…In our case, this is illustrated in Figure 4, showing an exponential decrease in R m with m. Note that Figure 4 yields for m = 1.5 a value of ρ 1.5 ≈ 3 × 10 −6 ΩmK −3/2 which is required in Equation (3). For metallic conductivity, the values of Rm and m in Equation ( 8) are correlated [77]. In our case, this is illustrated in Figure 4, showing an exponential decrease in Rm with m. Note that Figure 4 yields for m = 1.5 a value of ρ1.5 ≈ 3 × 10 −6 ΩmK −3/2 which is required in Equation (3).…”

“…For given values of V0, the Figure 3 demonstrates that model Equation ( 14) is also valid for the data of ordered, nonstoichiometric SFMO ceramics prepared by a solid-state reaction at 900 • C and sintered at 1280 • C for 12 h in a stream of 5%H 2 /Ar [74]. For metallic conductivity, the values of Rm and m in Equation ( 8) are correlated [77]. In our case, this is illustrated in Figure 4, showing an exponential decrease in Rm with m. Note that Figure 4 yields for m = 1.5 a value of ρ1.5 ≈ 3 × 10 −6 ΩmK −3/2 which is required in Equation (3).…”

Charge Puddles Driven Complex Crossover of Magnetoresistance in Non‐Topological Sulfur Doped Antimony Selenide Nanowires

“…Equation 5is analogous to the tunnelling magnetoresistance (TMR) discussed in various reports. [56,57] The magnetoresistance behavior of pristine sample P is simple, and it follows the WFS model. In case of nanotube sample SS2, as reported in our earlier work [31] sulfur plays an important role in creating a cross-over only in the low magnetic field, but the homogeneous distribution of sulfur in SS2 made it simple that only WFS and bipolaron models were sufficient to explain the MR behavior.…”

Advanced Magnetic Oxides (IWAMO‐2021)

“…The article by G. Suchaneck et al [1] reviews the resistivity behavior of granular SFMO ceramics comprising intergrain tunnel barriers. The low-field magnetoresistance properties in doubleperovskite SFMO core-shell structures arise from spin-dependent tunneling through a barrier formed by the shell.…”