Phase Diagram of Lattice–Spin System RbCoBr<sub>3</sub>

Nishiwaki, Yasushi; Todoroki, Norikazu

doi:10.1143/jpsj.75.024708

Cited by 9 publications

(3 citation statements)

References 12 publications

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“…the mean-field approximation. 18 As the temperature decreases, the sublattice magnetizations approach the unity and the perfect ferrimagnetic order is realized at temperatures near T = 17 K. This saturation temperature depends on J S 2 .…”

Section: Spin-latticementioning

confidence: 93%

“…We refer to this structure as "lattice-PD" or "↑-↓-0" in this paper. Nishiwaki and Todoroki 18 discussed the appearance of the three-sublattice ferrielectric state in RbCoBr 3 using the mean-field approximation. It is a structure with the ↑-↑-↓ configuration but the amount of displacement in each sublattice is different from the others, as shown in Fig.…”

Section: Theoretical Model a Structure Of Abx3 Compoundsmentioning

confidence: 99%

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Spin-lattice model of Magneto-electric Transitions in RbCoBr$_3$

Nakamura,

Nishiwaki

2008

Preprint

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Extensive Monte Carlo simulations are performed to analyze a recent neutron diffraction experiment on a distorted triangular lattice compound RbCoBr3. We consider a spin-lattice model, where both spin and lattice are Ising variables. This model explains well successive magnetic and dielectric transitions observed in the experiment. The exchange interaction parameters and the spin-lattice coupling are estimated. It is found that the spin-lattice coupling is important to explain the slow growth of a ferrimagnetic order. The present simulations were made possible by developing a new Monte Carlo algorithm, which accelerates slow Monte Carlo dynamics of quasi-one-dimensional frustrated systems.

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Section: Spin-latticementioning

confidence: 93%

Section: Theoretical Model a Structure Of Abx3 Compoundsmentioning

confidence: 99%

Spin-lattice model of Magneto-electric Transitions in RbCoBr$_3$

Nakamura,

Nishiwaki

2008

Preprint

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“…These rules are valid for the FM and AFM Ising chain systems Ca 3 Co 2 O 6 , CsCoCl 3 , CsCoBr 3 as well Ising chain compounds with distortions, e.g. TlCoCl 3 [23] and RbCoBr 3 [24]. * * * I am grateful to C. Demangeat and V. Uzdin for fruitful discussions.…”

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confidence: 84%

Magnetic structure and phase diagram in a spin-chain system: Ca ₃ Co ₂ O ₆

Kudasov¹

2007

Europhys. Lett.

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The low-temperature structure of the frustrated spin-chain compound Ca3Co2O6 is determined by the ground state of the 2D Ising model on the triangular lattice. At high-temperatures it transforms to the honeycomb magnetic structure. It is shown that the crossover between the two magnetic structures at 12 K arises from the entropy accumulated in the disordered chains. This interpretation is in an agreement with the experimental data. General rules for for the phase diagram of frustrated Ising chain compounds are formulated.PACS numbers: 75.25.+z, 75.30.Kz, 75.50.Ee A combination of a low dimensionality and frustration in magnetic compounds, which contain weakly bound Ising spin-chains packed into a two-dimensional (2D) frustrated lattice, gives rise to a complex magnetic behavior. Antiferromagnetic (AFM) Ising chains form the triangular lattice in well-known Ising-chain compounds CsCoCl 3 , CsCoBr 3 [1,2,3,4]. In these substances a partial AFM interchain order (honeycomb magnetic structure) appears just below the ordering temperature. While the temperature decreases, two magnetic phase transitions occur to low-temperature ferrimagnetic phases. A theoretical explanation of the magnetic structure of CsCoCl 3 , CsCoBr 3 was proposed by Mekata in the framework of a mean-field theory [1]. To describe the low-temperature phases an interaction between next nearest neighboring chains was included in the model. Recently, Ca 3 Co 2 O 6 has drawn considerable attention to a step-like magnetization curve [5,6,7,8,9]. The number of the steps in the curve depends strongly on a sweep rate of the external magnetic field and temperature [6,7,9]. Two steps become apparent in the temperature range from 12 K to 24 K [9]. The first step takes place at the zero magnetic field. Then the magnetic moment remains constant at about 1/3 of the full magnetization up to the magnetic field of 3.6 T where the second step occurs to the fully magnetized FM state. At least four equidistant steps are clearly visible below 12 K at a very low sweep rate. They are accompanied by a sizeable hysteresis. Similar phenomena were observed in other spin-chain compounds, e.g. Ca 3 CoRhO 6 [10,11].The structure of Ca 3 Co 2 O 6 consists of Co 2 O 6 chains running along the c axis. The Ca ions are situated between them. The chains are made up of alternating, facesharing CoO 6 trigonal prisms and CoO 6 octahedra. The crystalline electric field splits the energy level of Co 3+ions into the high-spin (S = 2) and low-spin (S = 0) states. The Co 3+ ions situated in the trigonal environment (CoI) are in the high-spin state and the octahedral Co sites (CoII) occurs in the low-spin state. In the last case the energy difference between the low-spin and * Electronic address: kudasov@ntc.vniief.ru high-spin states is very small and a tiny fraction of CoII sites is reported to be in the high-spin state. The crystalline electric field leads also to a very strong Ising-like anisotropy at the CoI sites. The chains form triangular lattice in the ab plane that is perpendicula...

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