Magnetic frustration control through tunable stereochemically driven disorder in entropy-stabilized oxides

Magnetic properties of high entropy oxides

“…1g. 43 Interestingly, increasing the amount of Co in the R-HEOs results in an inverse effect, the magnetic anisotropy becomes stronger and [110] becomes the preferred easy axis ( Fig. 1f and g).…”

“…68 In order to better elucidate the magnetic ordering, the T N is estimated using three different fitting approaches: (a) using the exchange parameters of the binary and ternary oxides indicating the T N ≈ 170 K ( Fig. 1c), (b) fitting the specific heat in the paramagnetic region with Curie-Weiss type behavior 38 Tailoring of the strength of the AFM with varying Co and Cu in R-HEO are shown in (e-g) 43 where (e) schematically shows the increase of the glassiness with Cu enrichment, likewise (f ) shows decrease/increase of the spin order with increase in Cu/Co and (g) indicates the change in the anisotropy energies for the [ resulting in the T N ≈ 118 K and (c) calculated directly from the HEO system using the singularity in the heat capacity yielding a T N ≈ 135 K. 68 The value identified from approach (b) is closest to the experimental value. Nevertheless, the other two approaches are also in close agreement with the experimental observations, especially if the short range correlations are considered.…”

“…69 To explore the stability limits of the AFM phase, epitaxial thin films of R-HEOs with varying composition were deposited on MgO substrates with a heterogeneous top layer of FM permalloy. 36,43 The magnetic heterogeneous interface so formed by the AFM R-HEOs and FM permalloy allows for strong exchange bias (EB) effects, which can be evaluated by estimating the shift of the hysteresis loop of the FM along the magnetic field axis due to interfacial exchange coupling with the adjacent AFM layer. 70 The strength of the EB effect depends on several factors, among which one of the important feature is the robustness of the AFM phase.…”

“…1e and f). 43 Also the magnetic isotropy, evaluated by analyzing the ratio of the anisotropy energies for the [100] and [110] directions, increases with amount of J-T active Cu 2+ in the R-HEO, as shown in Fig. 1g.…”

“…Currently, there are eight major classes of HEOs that can be categorized based on the crystallographic structures: rocksalt, 1,3,8,9 fluorite, [10][11][12][13][14][15] bixbyite, 10,12,16 perovskite (cubic, orthorhombic, rhombohedral), 5,[17][18][19] spinel, 20,21 pyrochlore, 7,[22][23][24] layered (Ruddlesden-Popper and delafossite) [25][26][27] and magnetoplumbite. 28,29 Likewise, a broad range of properties, such as electrochemical, 2,[30][31][32] optical, 11,[33][34][35] magnetic, 21,29,34,[36][37][38][39][40][41][42]43 electronic and ionic transport, [44][45]…”