Magnetic ground state, field-induced transitions, electronic structure, and optical band gap of the frustrated antiferromagnet 
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Pramanik, P.; Ghosh, Sheuly; Yanda, Premakumar; Joshi, D. C.; Suresh, Pittala; Sundaresan, A.; Mishra, Pankaj Kumar; Thota, Subhash; Seehra, M. S.

doi:10.1103/physrevb.99.134422

Cited by 29 publications

(48 citation statements)

References 59 publications

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“…In experiments, although various classes of breathing pyrochlore antiferromagnets such as the chromium oxides Li(Ga, In)Cr 4 O 8 [53, 59-66, 69, 70] and sulfides Li(Ga, In)Cr 4 S 8 [67,68,71] and the quantum magnet Ba 3 Yb 2 Zn 5 O 11 [72][73][74][75][76] have been studied, the ( 12 , 1 2 , 1 2 ) spin correlation has not been reported so far. On the other hand, the uniform pyrochlore antiferromagnets GeB 2 O 4 (B=Ni, Co, Fe, Cu) [77][78][79][80][81][82][83][84][85][86][87] do exhibit ( 12 , 1 2 , 1 2 ) magnetic LRO, although the experimentally proposed spin structure as well as the estimated exchange interactions (e.g., ferromagnetic J 1 ) seems to be different from the ones in the present theoretical model. If one can introduce the breathing alternation in the GeB 2 O 4 family, modifying the exchange interactions, the (…”

Section: Summary and Discussioncontrasting

confidence: 71%

Hedgehog-lattice spin texture in classical Heisenberg antiferromagnets on the breathing pyrochlore lattice

Aoyama

Kawamura

2021

Phys. Rev. B

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We theoretically investigate spin-lattice coupling (SLC) effects on the in-field ordering properties of classical Heisenberg antiferromagnets on the breathing pyrochlore lattice. Here, we use the two possible simplified models describing the effect of local lattice distortions on the spin ordering via the SLC, the bond-phonon and site-phonon models. It is found by means of Monte Carlo simulations that in both models, the 1 2 plateau shows up in the magnetization curve being relatively robust against the breathing bond-alternation, although magnetic long-range orders (LRO's) are realized only in the site-phonon model. In the bond-phonon model, additional further neighbor interactions are necessary to induce a magnetic LRO. In the site-phonon model, it is also found that in addition to the low-field, middle-field 1 2 -plateau, and high-field phases appearing on both the uniform and breathing pyrochlore lattices, various types of unconventional phases which can be viewed as LRO's in units of tetrahedron are induced by the breathing bond-alternation just below the 1 2 plateau and the saturation field. The occurrence of these tetrahedron-based orders could be attributed to the nature characteristic of the breathing pyrochlore lattice, i.e., the existence of the nonequivalent small and large tetrahedra. Experimental implications of our result are also discussed.

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Section: Summary and Discussioncontrasting

confidence: 71%

Hedgehog-lattice spin texture in classical Heisenberg antiferromagnets on the breathing pyrochlore lattice

Aoyama

Kawamura

2021

Phys. Rev. B

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“…In experiments, although various classes of breathing pyrochlore antiferromagnets such as the chromium oxides Li(Ga, In)Cr 4 O 8 [53, 59-66, 69, 70] and sulfides Li(Ga, In)Cr 4 S 8 [67,68,71] and the quantum magnet Ba 3 Yb 2 Zn 5 O 11 [72][73][74][75][76] have been studied, the ( 1 2 , 1 2 , 1 2 ) spin correlation has not been reported so far. On the other hand, the uniform pyrochlore antiferromagnets GeB 2 O 4 (B=Ni, Co, Fe, Cu) [77][78][79][80][81][82][83][84][85][86][87] do exhibit ( 1 2 , 1 2 , 1 2 ) magnetic LRO, although the experimentally proposed spin structure as well as the estimated exchange interactions (e.g., ferromagnetic J 1 ) seems to be different from the ones in the present theoretical model. If one can introduce the breathing alternation in the GeB 2 O 4 family, modifying the exchange interactions, the ( 1 2 , 1 2 , 1 2 ) hedgehog lattice might be realized.…”

Section: Summary and Discussioncontrasting

confidence: 71%

Spin ordering induced by lattice distortions in classical Heisenberg antiferromagnets on the breathing pyrochlore lattice

Aoyama

Kawamura

2019

Phys. Rev. B

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We theoretically investigate effects of lattice distortions on the spin ordering of classical Heisenberg antiferromagnets on the breathing pyrochlore lattice. In the model, local lattice distortions originating from the site vibration are taken into account to yield effective spin interactions via the spin-lattice coupling (SLC). The breathing lattice-alternation is characterized by the ratio of the nearest-neighbor interaction for large tetrahedra to that for small ones, J ′ /J. It is found by Monte Carlo simulations that the system exhibits a first-order transition into four different types of collinear magnetic ordered states. In the uniform case (J ′ /J = 1), the state realized at stronger SLC is cubic-symmetric characterized by the ( 1 2 , 1 2 , 1 2 ) magnetic Bragg peaks, while the one at weaker SLC is tetragonal-symmetric characterized by the (1, 1, 0) ones. With increasing the breathing distortion (decreasing J ′ /J), the ordering pattern of the ( 1 2 , 1 2 , 1 2 ) state becomes non-cubic with its magnetic Bragg reflections almost unchanged, while the (1, 1, 0) state is robust. The non-cubic state peculiar to the breathing pyrochlores is further categorized into two types. We demonstrate that these two non-cubic orderings result in the massive degeneracy of the ground state and that the associated residual entropy per spin takes characteristic values of ≃ ln(4) 16 kB and ≃ ln(6) 16 kB. Experimental implications of the results are discussed.

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“…It will also be intriguing to explore the Kitaev-type interactions in the Co 2+based compounds on other lattice structures [67]. The candidates include quasi-two- [110], and Ba 2 La 2 CoTe 2 O 12 [111], and three-dimensional compounds, such as a spinel GeCo 2 O 4 [112,113] and pyrochlores NaCaCo 2 F 7 and NaSrCo 2 F 7 [114,115,116,117]. Besides Co 2+ , Ni 3+ is also a candidate for the high-spin d 7 magnetic ion as listed in table 1.…”

Section: High-spin D 7 Systemsmentioning

confidence: 99%

Materials design of Kitaev spin liquids beyond the Jackeli–Khaliullin mechanism

Motome

Sano

Jang

et al. 2020

J. Phys.: Condens. Matter

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The Kitaev spin liquid provides a rare example of well-established quantum spin liquids in more than one dimension. It is obtained as the exact ground state of the Kitaev spin model with bond-dependent anisotropic interactions. The peculiar interactions can be yielded by the synergy of spin-orbit coupling and electron correlations for specific electron configuration and lattice geometry, which is known as the Jackeli-Khaliullin mechanism. Based on this mechanism, there has been a fierce race for the materialization of the Kitaev spin liquid over the last decade, but the candidates have been still limited mostly to 4d-and 5d-electron compounds including cations with the low-spin d 5 electron configuration, such as Ir 4+ and Ru 3+ . Here we discuss recent efforts to extend the material perspective beyond the Jackeli-Khaliullin mechanism, by carefully reexamining the two requisites, formation of the j eff = 1/2 doublet and quantum interference between the exchange processes, for not only dbut also f -electron systems. We present three examples: the systems including Co 2+ and Ni 3+ with the high-spin d 7 electron configuration, Pr 4+ with the f 1 -electron configuration, and polar asymmetry in the lattice structure. In particular, the latter two are intriguing since they may realize the antiferromagnetic Kitaev interactions, in contrast to the ferromagnetic ones in the existing candidates. This partial overview would stimulate further material exploration of the Kitaev spin liquids and its topological properties due to fractional excitations.

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Magnetic ground state, field-induced transitions, electronic structure, and optical band gap of the frustrated antiferromagnet GeCo2O4

Cited by 29 publications

References 59 publications

Hedgehog-lattice spin texture in classical Heisenberg antiferromagnets on the breathing pyrochlore lattice

Hedgehog-lattice spin texture in classical Heisenberg antiferromagnets on the breathing pyrochlore lattice

Spin ordering induced by lattice distortions in classical Heisenberg antiferromagnets on the breathing pyrochlore lattice

Materials design of Kitaev spin liquids beyond the Jackeli–Khaliullin mechanism

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