Orbital fluctuations and orbital order in FeCr2S4

Tsurkan, V.; Fritsch, V.; Nidda, H.-A. Krug von; Büttgen, N.; Samusi, D.; Körner, Stefan; Scheidt, E.‐W.; Horn, S.; Tidecks, R.; Loidl, A.

doi:10.1016/j.jpcs.2005.09.041

Cited by 32 publications

(26 citation statements)

References 28 publications

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“…2 (a) and (b) for the range 0.05 ≤ B ≤ 0.2 T and 1.0 ≤ B ≤ 7.0 T, respectively. As was reported by previous studies [9,13], M(T ) shows a step-like anomaly in ZFC and FC process at around orbital ordering temperature T OO ∼9 K. This anomaly comes from changing the orbital degree of freedom [9], and indicates that the spin in this system is strong coupled with the lattice. We determined T OO as a point at which ∂M(T )/∂T of FC process has a local minimum.…”

Section: Methodssupporting

confidence: 79%

“…The orbital order transition may occur simultaneously with the magnetic phase transition of III at T OO . It is reported that C P (T ) of FeCr 2 S 4 has a tail just above T OO in high magnetic field ∼10T [9,12]. This might be referred to the phase transition from III to I phase.…”

Section: B-t Phase Diagrammentioning

confidence: 96%

“…Therefore, 1.6µ B ( = 2Cr 3+ − Fe 2+ ) is expected as the saturated magnetic moment, assuming the collinear type ferrimangetic structure. In a low magnetic field range, temperature T dependence of magnetization M(T ) has a peak at around T m = 70 K, and M(T ) decreases with decreasing T below T m [9,10,11,12,13,14]. An irreversibility of magnetization between zero-field-cooled (ZFC) and field-cooled (FC) procedures is observed below T N in a low B range, and is reduced with increasing B [11,12,13].…”

Section: Introductionmentioning

confidence: 99%

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Magnetic properties of spinel FeCr2S4 in high magnetic field

Ito

Nagi

Kado

et al. 2011

Journal of Magnetism and Magnetic Materials

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We studied temperature and magnetic field dependence of magnetization, M(T ) and M(B), on thiospinel FeCr 2 S 4 . We observed a step-like anomaly at T OO ∼ 9 K for M(T ) attributed to an orbital order transition in magnetic field 0 < B ≤ 7 T. Furthermore, also for M(B), an step-like anomaly appears at B c ∼ 5.5 T below T OO . This suggests an existence of a magnetic phase boundary at B c in T < T OO . Because the anomaly at B c of M(B) exists in the orbital ordered phase, the spin structure of FeCr 2 S 4 in T < T OO is strongly coupled with the lattice of the system.

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Section: Methodssupporting

confidence: 79%

Section: B-t Phase Diagrammentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Magnetic properties of spinel FeCr2S4 in high magnetic field

Ito

Nagi

Kado

et al. 2011

Journal of Magnetism and Magnetic Materials

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“…The observed high-field magneto-structural states are discussed within a H-T phase diagram taking into account the field and temperature evolution of three coexisting spin structures and subsequent lattice transformations induced by magnetic field. Frustrated magnets with spinel structure AB 2 X 4 manifest an intriguing behavior and unusual ground states, such as composite spins [1], spin dimerization [2,3], heavy-fermion properties [4,5], spin-orbital liquid [6], and orbital glass [7,8] which originate from magnetic frustration but also from the intimate interplay of spin, charge and orbital degrees of freedom and their coupling to the lattice. In the magnetic B -site Cr spinels with strong spin-phonon coupling, a novel type of structural transformation has been identified experimentally, the so called spin Jahn-Teller effect [9][10][11][12].…”

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confidence: 99%

Magnetostructural Transitions in a Frustrated Magnet at High Fields

et al. 2011

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Ultrasound and magnetization studies of bond-frustrated ZnCr2S4 spinel are performed in static magnetic fields up to 18 T and in pulsed fields up to 62 T. At temperatures below the antiferromagnetic transition at TN1 ≈ 14 K the sound velocity as function of magnetic field reveals a sequence of steps followed by plateaus indicating a succession of crystallographic structures with constant stiffness. At the same time, the magnetization evolves continuously with field up to full magnetic polarization without any plateaus in contrast to geometrically frustrated chromium oxide spinels. The observed high-field magneto-structural states are discussed within a H-T phase diagram taking into account the field and temperature evolution of three coexisting spin structures and subsequent lattice transformations induced by magnetic field. [7,8] which originate from magnetic frustration but also from the intimate interplay of spin, charge and orbital degrees of freedom and their coupling to the lattice. In the magnetic B -site Cr spinels with strong spin-phonon coupling, a novel type of structural transformation has been identified experimentally, the so called spin Jahn-Teller effect [9][10][11][12]. In an octahedral crystal field the t 2g levels of the Cr 3+ ions are half filled and the spin-orbit coupling is negligible. Therefore, the conventional Jahn-Teller scenario related to magnetic ions with an orbitally degenerate state is not applicable here, and the structural deformation is believed to be driven purely by spin ordering. The ground-state properties of frustrated magnets are characterized by a large degeneracy and are highly susceptible to external perturbations. An external magnetic field can change the balance between the competing interactions, and unusual phenomena, such as magnetization plateaus at half or fractional saturation are observed [13,14].In geometrically frustrated ACr 2 X 4 oxide (X=O) spinels the Cr ions forming a pyrochlore lattice of cornersharing tetrahedra are strongly coupled by direct antiferromagnetic (AFM) interactions of the order of 100 -400 K. Emerging phenomena in geometrically frustrated oxides are dominated by local "tetrahedron" physics [15,16]. In sulphide (X=S) and selenide (X=Se) spinels the direct AFM exchange is reduced due to the increasing distance between the magnetic ions and at the same time 90 o ferromagnetic (FM) exchange becomes important. Where FM and AFM exchanges are of comparable strength, the ground state again is strongly frustrated, a situation which has been named bond frustration [17].In ZnCr 2 S 4 , subject of the present study, competing FM and AFM interactions indeed are of equal strength resulting in a Curie-Weiss temperature close to zero [11]. Neutron-diffraction measurements [18][19][20] established two subsequent magnetic transitions in ZnCr 2 S 4 : the first one to an incommensurate helical AFM order at T N 1 ≈ 14 K, and the second one, to coexisting commensurate spin order at T N 2 ≈ 7 K. The helical state is characterized by a spin spiral with a prop...

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“…In addition to the CMR effect and gigantic Kerr rotation, temperature dependence of low-field magnetization shows a cusp-like anomaly around 60 K for single-crystal sample, a cusp-like anomaly around 70 K and a step-like transition around 9 K for polycrystalline sample [1,4,9]. Both single-crystal and polycrystalline samples show irreversibility between zero-fieldcooling (ZFC) and field-cooling (FC) sequence [8,9]. Below the first anomaly temperature 60 K, transmission electron microscopy studies on single-crystal sample revealed a structural transition indicating a cubic-to-triclinic symmetry reduction within crystallographic domains [10].…”

Section: Introductionmentioning

confidence: 96%