Transverse susceptibility as a probe of the magnetocrystalline anisotropy-driven phase transition inPr0.5Sr0.5CoO

Abstract

Half-doped Pr 1-x Sr x CoO 3 (x=0.5) displays anomalous magnetism most notably manifest in the field-cooled magnetization versus temperature curves under different applied cooling fields.Recently, an explanation was advanced that a magnetocrystalline anisotropy transition driven by a structural transition at 120 K is the origin of this behavior. In this paper, we further elucidate the nature of the magnetic anisotropy across the low temperature phase transition in this material by means of transverse susceptibility (TS) measurements performed using a self-resonant tunnel diode oscillator. TS probes magnetic materials by means of a small radio frequency oriented transverse to a DC field which sweeps from positive to negative saturation. TS scans as a function of field clearly reveal peaks associated with the anisotropy (H K ) and switching fields (H S ). When peak position is examined as a function of temperature, around 120 K the signature of a ferromagnetic to ferromagnetic (FM-FM) phase transition is evident as a sharp feature in H K and a corresponding cusp in H S . A third TS peak (not previously observed in other classes of magnetic oxides such as manganites and spinel ferrites) is found to be correlated with the crossover field (H cr ) in the unconventional magnetization versus temperature (M(T)) behavior. 2We observe a strong temperature dependence of H cr around 120 K using this technique, which suggests the magnetic field-influenced magnetocrystalline anisotropy transition. We show the switching between the high-field magnetization state and the low-field magnetization state associated with the magnetocrystalline anisotropy transition is irreversible when the magnetic field is re-cycled. Finally, we demonstrate that the TS peak magnitude indicates easy axis switching associated with this phase transition, even in these polycrystalline samples. Our results further confirm that TS provides new insights into the magnetic behavior of complex oxides. 75.30.Gw, 75.47.Lx, 75.30.Cr PACS:

Enhanced room-temperature spin Seebeck effect in a YIG/C60/Pt layered heterostructure

“…A detailed description of the TS measurements can be found in our earlier papers. [19][20][21] Figures 3a and 3b show the TS spectra of the YIG/Pt and YIG/C 60 /Pt samples at room temperature. As the DC magnetic field was swept from positive to negative saturation, two peaks were observed in the positive quadrant.…”

“…Over the years, we have established the TS technique as a direct, accurate probe of effective magnetic anisotropy field (H K ) for a wide range of magnetic materials. [19][20][21] In this method, sample is placed inside an inductive coil which is part of the TDO circuit. An RF perturbation field is applied perpendicular to the DC field.…”

Magnetostructural coupling, magnetic ordering, and cobalt spin reorientation in metallicPr0.5Sr0.5CoO

“…19 Evidences of the interplay between the magnetic and crystal structures were obtained from transverse susceptibility and magnetostriction measurements which point to likely changes in the magnetocrystalline anisotropy at T S1 . [12][13][14]20 Lorentz Transmission Electron Microscopy (LTEM) images reported by Uchida et al also suggested a reorientation of the magnetization axis by 45º when studying the evolution of the magnetic domain structure under electronbeam. 21 The importance of the spin-lattice coupling has been also confirmed by means of xray magnetic circular dichroism (XMCD) experiments at the Co L 2,3 edges.…”

“…The discovery of a second magnetic transition and intriguing step-like behavior of the magnetization, which decreases or increases depending on the magnitude of the applied field, [12][13][14][15][16] was followed by the detection of structural anomalies at the same temperature by…”

“…[1][2][3][4] In this context, the physical properties of half-doped Pr-based Pr 0.50 A 0.50 CoO 3 specimens are attracting the interest due to the observation of nonconventional phase transitions and distinct unexpected properties with A=Ca 4-11 and Sr. [12][13][14][15][16][17][18] In this way, Ca valence shift. [7][8][9] Pr 0.50 Ca 0.50 CoO 3 (PCCO) is orthorhombic (Pnma) and metallic but it becomes insulating at T MI ~ 80 K. An electron is transferred from some Pr atoms to Co sites [6][7][8][9][10] and a concomitant SS crossover promotes the stabilization of the Co 3+ low spin (LS) state.…”