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Nii, Yoichi; Sagayama, Hajime; Arima, T.; Aoyagi, Shinobu; Sakai, Ryosuke; Maki, Seijiro; Nishibori, Eiji; Sawa, Hiroshi; Sugimoto, Kunihisa; Ohsumi, H.; Takata, Masaki

doi:10.1103/physrevb.86.125142

Cited by 82 publications

(114 citation statements)

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“…On the other hand, the FM transition temperature T N1 , which corresponds to We discuss the origin of the phase transitions for x = 0.1 and 0.2. From the previous studies on FeV 2 O 4 [4,6], lattice distortion at T s is derived from cooperative JT effect of Fe 2+ ions, where two of three e orbital electrons occupy 3z 2 -r 2 orbital with lower energy. Therefore, FeO 4 tetrahedron is compressed along c-axis.…”

Section: Resultsmentioning

confidence: 99%

“…Further, spin-glass behavior was observed at 85 K [7], and magnetic field dependent ferroelectricity was found [8][9][10]12]. Very recently, orbital states of Fe 2+ and V 3+ ions were studied using single crystal X-ray diffraction experiments and first-principles electronic structure calculation [6,11], and it was reported that the cooperative Jahn-Teller (JT) effects and relativistic spin-orbit (SO) coupling play an important role in the phase transitions. Nii et al also proposed the orbital order of V 3+ ions containing complex orbital states at T N2 [6].…”

Section: Introductionmentioning

confidence: 99%

“…Recently, vanadium spinels AV 2 O 4 , where the divalent A 2+ (A = Mn, Fe, Co, Zn, Mg, and Cd) and the trivalent V 3+ ions occupy the tetrahedral (A-site) and the octahedral (B-site) sites in a normal spinel structure, respectively, have been studied intensively because of the variety of interesting phenomena related with orbital degrees of freedom because the V 3+ ions have 3d 2 configurations in the triply degenerate t 2g level [1][2][3][4][5][6][7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

“…Among the vanadium spinels, FeV 2 O 4 is a unique compound because the Fe 2+ (3d 6 ) ions have the orbital degrees of freedom in the doubly degenerate e states. This compound exhibits the successive structural phase transitions from a cubic to a tetragonal phase (tetraHT; c < a) at T s = 140 K, from a tetraHT to an orthorhombic (ortho) phase at 110 K, and from an orthorhombic to another tetragonal phase (tetraLT; c > a) at 60 K [4].…”

Section: Introductionmentioning

confidence: 99%

“…Very recently, orbital states of Fe 2+ and V 3+ ions were studied using single crystal X-ray diffraction experiments and first-principles electronic structure calculation [6,11], and it was reported that the cooperative Jahn-Teller (JT) effects and relativistic spin-orbit (SO) coupling play an important role in the phase transitions. Nii et al also proposed the orbital order of V 3+ ions containing complex orbital states at T N2 [6]. Whereas, a study on soft x-ray magnetic circular dichroism suggests a orbital order of V 3+ ions containing a real orbital states [13].…”

Section: Introductionmentioning

confidence: 99%

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Structural and Magnetic Properties in Spinel Oxide Fe₁₋_xMn_xV₂O₄

Kawaguchi¹,

Ishibashi²,

Miki³

et al. 2014

Proceedings of the 12th Asia Pacific Physics Conference (APPC12)

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Structural properties in spinel oxide Fe 1−x Mn x V 2 O 4 for x ≤ 0.4 have been studied using synchrotron powder diffraction experiments. The successive structural phase transitions similar to those observed in FeV 2 O 4 are observed for x = 0.1. Whereas, the only lattice distortion of cubic-to-tetragonal (c > a) is observed for x = 0.3 and 0.4. Furthermore, we have also measured the magnetization and heat capacity. The results indicate that the temperatures of magnetic phase transitions at ferrimagnetic and non-collinear ferrimagnetic order for x ≤ 0.2 correspond to those of structural transitions of orthorhombic and tetragonal (c > a), respectively. On the other hand, the temperatures of ferrimagnetic phase transition for x = 0.3 and 0.4 are consistent with those of structural transition of a cubic-totetragonal phase (c > a). These results are discussed in terms of orbital state of Fe 2+ and V 3+ ions considering the Jahn-Teller effects and spin-orbit coupling.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Structural and Magnetic Properties in Spinel Oxide Fe₁₋_xMn_xV₂O₄

Kawaguchi¹,

Ishibashi²,

Miki³

et al. 2014

Proceedings of the 12th Asia Pacific Physics Conference (APPC12)

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Magnetocaloric Materials with Multiple Instabilities

2017

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the cases of H = 0 and H ≠ 0. In the zero field, the entropy exhibits an anomaly at a ferromagnetic (or ferrimagnetic) transition temperature (T C ), where the slope changes. As a magnetic field is applied to the material at around T C , the fluctuation is suppressed and the entropy is reduced. By exploiting this effect and combining several processes to form a thermodynamic cycle, e.g., Brayton cycle (i)→(ii)→(iii)→(iv)→(i), [7] heat can be extracted from the magnetic material to the thermal bath.While there are several prerequisites (e.g., magnetic and thermal hysteresis properties, mechanical stability, etc.) for materials to be applied to magnetic refrigeration, the enhanced magnitude of the magnetocaloric effect is of primary importance. The magnitude of the magnetocaloric effect is usually evaluated as the isothermal entropy change ΔS = S(H, T) -S(H = 0, T), or adiabatic temperature change ΔT, which are illustrated in Figure 1a, for a given magnetic field change ΔH. In many cases, the isothermal entropy change ΔS is adopted to argue the magnetocaloric effect as it is easier to experimentally evaluate than the adiabatic temperature change ΔT. Here, ΔS is calculated from a series of MH curves with a fine temperature interval using the Maxwell relationRecent research on magnetocaloric materials has focused on first-order magnetic transition systems, rather than secondorder ones because of the enhanced magnitude of the magnetocaloric effect in the former class of materials. [1] In second-order transition systems, the entropy value itself is continuous as a function of temperature, and only its temperature derivative is discontinuous, as shown in the upper panel of Figure 1b. Thus, the entropy change -ΔS displays a triangular-like shape with broad tails at both the high-and low-temperature sides. In this case, the maximum value of -ΔS is generally not very large. On the other hand, in the case of the first-order transition, the entropy itself changes discontinuously at the transition temperature, and therefore, the isothermal entropy change -ΔS tends to be large in magnitude for a rather narrow range of temperatures, as illustrated in Figure 1c. At the same time, the temperature profile of -ΔS indicates a rectangular-like shape rather than the triangular shape in the case of the secondorder transition. Based on these arguments, first-order transition systems have more widely been investigated than secondorder transition systems. Representative examples showing the The magnetocaloric effect is a well-known phenomenon where the temperature of a magnetic material varies upon application or removal of a magnetic field. This effect is anticipated to be applied to magnetic refrigeration technology, which is environmentally benign. For practical applications, it is essential to explore and expand the materials horizon of novel magnets that exhibit giant magnetocaloric effects to achieve sufficient cooling efficiency. In this article, several attempts to enhance the magnetocaloric effect are reviewed from the viewpoint...

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Magnetic and Magnetodielectric Properties of Epitaxial Iron Vanadate Thin Films

Zhou

Takahashi

Zhou

et al. 2016

Adv Elect Materials

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We report on the magnetic and magnetodielectric behavior of epitaxial (001) transition metal oxide spinel iron vanadate (Fe 1+x V 2-x O 4 -FVO) thin films grown on (001) SrTiO 3 substrates by pulsed laser deposition. X-ray absorption spectroscopy (XAS) studies confirm the trivalent and nominally divalent nature of V and Fe ions, respectively, whilst an excess of Fe 3+ ions was also found. Aberrationcorrected cross-sectional scanning transmission electron microscopy analysis suggests that the excess Fe 3+ may be accommodated through Fe 3 O 4 stacking faults along the {111} planes. Temperaturedependent X-ray magnetic circular dichroism (XMCD) spectra revealed an anti-parallel alignment of spins between the Fe 2+ and V 3+ cations. M-H loops acquired at 10 K, well below the non-collinear ferromagnetic phase transition temperature, show magnetic anisotropy and point to the existence of two distinct phases with different coercive fields. Visual evidence for magnetic domains and their switching is given by magnetic force microscopy, which finds a switching field of ~ 3 T in agreement with the M-H loops. Magnetodielectric measurements for a Pd/FVO/Nb:STO heterostructure revealed a weak hysteresis in the magneto-capacitance loops at 10 K, thus confirming magneto-dielectric coupling. Detailed temperature and frequency dependent dielectric studies found that Maxwell-Wagner-type relaxation dominates capacitance behaviour above ~ 40 K due to a FVO/Nb:SrTiO 3 Schottky interface.Received: ((will be filled in by the editorial staff))Revised: ((will be filled in by the editorial staff))

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Orbital structures in spinel vanadatesAV2O4(A

Cited by 82 publications

References 23 publications

Structural and Magnetic Properties in Spinel Oxide Fe₁₋_xMn_xV₂O₄

Structural and Magnetic Properties in Spinel Oxide Fe₁₋_xMn_xV₂O₄

Magnetocaloric Materials with Multiple Instabilities

Magnetic and Magnetodielectric Properties of Epitaxial Iron Vanadate Thin Films

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Orbital structures in spinel vanadatesAV2O4(A

Cited by 82 publications

References 23 publications

Structural and Magnetic Properties in Spinel Oxide Fe1−xMnxV2O4

Structural and Magnetic Properties in Spinel Oxide Fe1−xMnxV2O4

Magnetocaloric Materials with Multiple Instabilities

Magnetic and Magnetodielectric Properties of Epitaxial Iron Vanadate Thin Films

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Structural and Magnetic Properties in Spinel Oxide Fe₁₋_xMn_xV₂O₄

Structural and Magnetic Properties in Spinel Oxide Fe₁₋_xMn_xV₂O₄