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Hollmann, N.; Agrestini, S.; Hu, Z.; He, Zhidong; Schmidt, Marcus; Kuo, Chang Yang; Rotter, Martin; Nugroho, A. A.; Sessi, Violetta; Tanaka, A.; Brookes, N. B.; Tjeng, L. H.

doi:10.1103/physrevb.89.201101

Cited by 41 publications

(40 citation statements)

References 36 publications

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“…However, the global average of the magnetic moment along the b-axis (M b ) obtained by the 2k solution is 4.3(3) µ B . This is close to the value in αCVO where there is large spin-orbit coupling (SOC) 17,[27][28][29] . Crystallographic structure analysis shows that the distortion of the CoO 6 -octahedron is much weaker in γCVO than in αCVO 30 .…”

Section: Resultssupporting

confidence: 79%

“…We point out that the 2k solution is inconsistent with this value. On the other hand, the phase separation model produces M b = 3.04(9) µ B /Co, in excellent agreement with magnetization, XMCD data, as well as theoretical predictions 18,19,21,26,29,31 .…”

Section: Resultssupporting

confidence: 79%

“…-0.61 µ B /Co(1) and -0.01 µ B /Co(1), respectively, in the k 1 phase, the additional non-negligible in-plane magnetic moments obtained in our refinements strongly indicate that the spins in γCVO do not lie solely along the b-axis. This might be related to the complex CoO 6 -octahehral distortion seen in this compound 29,31 .…”

Section: Resultsmentioning

confidence: 86%

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Unconventional magnetic phase separation in γ-CoV2O6

et al. 2017

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We have explored the magnetism in the non-geometrically frustrated spin-chain system γ-CoV2O6 which possesses a complex magnetic exchange network. Our neutron diffraction patterns at low temperatures (T T N = 6.6 K) are best described by a model in which two magnetic phases coexist in a volume ratio 65(1) : 35(1), with each phase consisting of a single spin modulation. This model fits previous studies and our observations better than the model proposed by Lenertz et al in J. Phys. Chem. C 118, 13981 (2014), which consisted of one phase with two spin modulations. By decreasing the temperature from T N , the minority phase of our model undergoes an incommensuratecommensurate lock-in transition at T * = 5.6 K. Based on these results, we propose that phase separation is an alternative approach for degeneracy-lifting in frustrated magnets.

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Section: Resultssupporting

confidence: 79%

Section: Resultssupporting

confidence: 79%

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Unconventional magnetic phase separation in γ-CoV2O6

et al. 2017

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“…Generally, the dipole selection rules in the X‐ray absorption spectroscopy (XAS) data at the 3d transition metal L 2,3 edges are very effective in determining which of the 2p 5 3d n+ 1 final states can be reached and with what intensity, starting from a particular 2p 6 3d n initial state. This makes the technique an extremely sensitive probe for the valence state, spin state, and local symmetry of 3d TM in the solid state 15–18. Figure 3 presents the Co‐ L 2,3 XAS spectra of BaCoSO and YBaCo 3 AlO 7 19 (Co 2+ with a tetrahedral local coordination).…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of Ba[CoSO]: Magnetic Complexity in the Presence of Chalcogen Ordering

Valldor

Rößler

Prots

et al. 2015

Chemistry A European J

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Barium thio-oxocobaltate(II), Ba[CoS2/2 O2/2 ], was synthesized by the reaction of equimolar amounts of BaO, Co, and S in closed silica ampoules. The title compound (Cmcm, a=3.98808(3), b=12.75518(9), c=6.10697(4) Å) is isostructural to Ba[ZnSO]. The use of soft X-ray absorption spectroscopy confirmed that cobalt is in the oxidation state +2 and tetrahedrally coordinated. Its coordination consists of two sulfur and two oxygen atoms in an ordered fashion. High-temperature magnetic susceptibility data indicate strong low-dimensional spin-spin interactions, which are suggested to be closely related to the layer-type crystal structure and perhaps the ordered distribution of sulfur and oxygen. Antiferromagnetic ordering below TN =222 K is observed as an anomaly in the specific heat, coinciding with a significant lowering of the magnetic susceptibility. Density functional theory calculations within a generalized-gradient approximation (GGA)+U approach identify an antiferromagnetic ground state within the square-like two-dimensional layers of Co, and antiferromagnetic correlations for nearest and next nearest neighbors along bonds mediated by oxygen or sulfur. However, this magnetic state is subject to frustration by relatively strong interlayer couplings.

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“…In a fully relativistic treatment there is an additional orbital correction, referred to as orbital polarization (OP), 20,21 which is an attractive energy that is proportional to the square of the orbital angular moment L. This OP correction has successfully been applied to intermetallics and especially to Co compounds that exhibit a large Co orbital moment. [22][23][24][25][26][27] The OP correction can be implemented in a phenomenological approach analogous to Hund's second rule that is implicit in GGA. Our results will show that orbital effects are indeed much larger within the OP scheme than within conventional GGA+U.…”

Section: Structure Of Ccvo and Calculation Methodsmentioning

confidence: 99%

Strong interactions, narrow bands, and dominant spin-orbit coupling in Mott insulating quadruple perovskiteCaCo3V4O12

Rhee

Pickett

2014

Phys. Rev. B

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We investigate the electronic and magnetic structures and the character and direction of spin and orbital moments of the recently synthesized quadruple perovskite compound CaCo3V4O12 using a selection of methods from density functional theory. Implementing the generalized gradient approximation and the Hubbard U correction (GGA+U), ferromagnetic spin alignment leads to half-metallicity rather than the observed narrow gap insulating behavior. Including spin-orbit coupling (SOC) leaves a Mott insulating spectrum but with negligible gap. SOC is crucial for the Mott insulating character of the V d 1 ion, breaking the dm=±1 degeneracy and also giving a substantial orbital moment. Evidence is obtained of the large orbital moments on Co that have been inferred from the measured susceptibility. Switching to the orbital polarization (OP) functional, GGA+OP+SOC also displays clear tendencies toward very large orbital moments but in its own distinctive manner. In both approaches, application of SOC, which requires specification of the direction of the spin, introduces large differences in the orbital moments of the three Co ions in the primitive cell. We study a fictitious but simpler cousin compound Ca3CoV4O12 (Ca replacing two of the Co atoms) to probe in more transparent fashion the interplay of spin and orbital degrees of freedom with the local environment of the planar CoO4 units. The observation is made that the underlying mechanisms seems to be local to a CoO4 plaquette, and that there is very strong coupling of the size of the orbital moment to the spin direction. These facts strongly suggest non-collinear spins, not only on Co but on the V sublattice as well.

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Spectroscopic evidence for exceptionally high orbital moment induced by local distortions inα-CoV2O6

Cited by 41 publications

References 36 publications

Unconventional magnetic phase separation in γ-CoV2O6

Unconventional magnetic phase separation in γ-CoV2O6

Synthesis and Characterization of Ba[CoSO]: Magnetic Complexity in the Presence of Chalcogen Ordering

Strong interactions, narrow bands, and dominant spin-orbit coupling in Mott insulating quadruple perovskiteCaCo3V4O12

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