Investigations of Two-Dimensional Ferromagnet K<sub>2</sub>CuF<sub>4</sub> by Neutron Scattering

Hirakawa, Kazuomi; Ikeda, Hironobu

doi:10.1143/jpsj.35.1328

Cited by 127 publications

(38 citation statements)

References 27 publications

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“…We also apply the power law in Eq. (1) [29,30], the crossover from quasi-2D BEC to 3D BEC described by setting φ = 3/2 is expected to occur at approximately 20 mK, which is much lower than the present temperature range.…”

Section: Resultsmentioning

confidence: 60%

“…However, this prediction has not been sufficiently verified experimentally. To explore the quasi-2D BEC of lattice bosons and its critical behavior, we performed magnetization and specific heat measurements on K 2 CuF 4 , which is described as a spin-1/2, quasi-2D, square-lattice XXZ ferromagnet with weak easy-plane anisotropy [22][23][24][25][26][27][28][29][30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

“…The last term is the Zeeman term. The exchange parameters and g factor were obtained as [29,30] and g = 2.093 [31]. Because J ≫ J ′ and J A > 0, K 2 CuF 4 is magnetically described as a spin-1/2, quasi-2D XXZ ferromagnet with weak anisotropy of the easy-plane type.…”

Section: Introductionmentioning

confidence: 99%

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Quasi-two-dimensional Bose-Einstein condensation of lattice bosons in the spin- 12 XXZ ferromagnet K2CuF4

et al. 2017

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K2CuF4 is magnetically described as a spin-1/2, quasi-two-dimensional (2D), square-lattice XXZ ferromagnet with weak easy-plane anisotropy. The magnetic ordering for an applied magnetic field H parallel to the c axis is equivalent to the Bose -Einstein condensation (BEC) of lattice bosons, as discussed by Matsubara and Matsuda [Prog. Theor. Phys. 16, 569 (1956)]. Magnetization and specific heat measurements were performed to obtain the temperature vs magnetic field phase diagram for H c. The phase boundary between polarized and ordered phases was found to be expressed by the power law Hc(T ) − Hc(0) ∝ T φ with exponent φ ≈ 1.0 in a wide temperature range, in agreement with the theory of quasi-2D BEC.

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Section: Resultsmentioning

confidence: 60%

Section: Introductionmentioning

confidence: 99%

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Quasi-two-dimensional Bose-Einstein condensation of lattice bosons in the spin- 12 XXZ ferromagnet K2CuF4

et al. 2017

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“…K 2 CuF 4 is a layered double perovskite that belongs to the class of K 2 M F 4 (M =Mn, Fe, Co, Ni, Cu) [15] materials. Its crystal structure was an object of intense research more than three decades ago [16][17][18]. The bulk system is built up from layers with a respective thickness of three atoms in an alternate stacking (Fig.…”

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confidence: 99%

Ferromagnetic two-dimensional crystals: Single layers of K2CuF4

et al. 2013

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The successful isolation of graphene ten years ago has evoked a rapidly growing scientific interest in the nature of two-dimensional (2D) crystals. A number of different 2D crystals has been produced since then, with properties ranging from superconductivity to insulating behavior. Here, we predict the possibility for realizing ferromagnetic 2D crystals by exfoliating atomically thin films of K2CuF4. From a first-principles theoretical analysis, we find that single layers of K2CuF4 form exactly 2D Kosterlitz-Thouless systems. The 2D crystal can form a free-standing membrane, and exhibits an experimentally accessible transition temperature and robust magnetic moments of 1µB per formula unit. 2D K2CuF4 unites ferromagnetic and insulating properties and is a demonstration of principles for nanoelectronics such as novel 2D-based heterostructures.Introduction The large variety of two-dimensional (2D) atomic crystals which are available to us [1, 2] comprise into a very rich class of materials, which collectively covers a large diversity of properties. Also, the recent progress in creating heterostructures made from individual atomic crystals [3][4][5] allowed the investigation of such phenomena as Coulomb drag [6] and the Hofstadter butterfly [7][8][9], but also facilitated the creation of novel, often multifunctional devices, such as tunneling transistors [10,11] and photovoltaic devices [12][13][14].

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“…K 2 CuF 4 exhibits a 1.0 B localized magnetic moment on each Cu atom ͑at Tϭ0 K͒ lying on ab planes [42][43][44] forming a quasi-2D Heisenberg ferromagnetic system at low temperature with a small XY anisotropy ͑ϳ1%͒. The Curie temperature of this compound is 6.25 K, [42][43][44] the magnetic coupling constant has been determined from thermal analysis, 44 and by neutron diffraction 43 and is in the range 15-23 K. The KK orbital ordering of the magnetic planes was also invoked to explain the observed magnetic order. 42 Recent theoretical works on electronic and magnetic properties of K 2 CuF 4 are from local density approximation ͑LDA͒, 45 and from ab initio derived Hubbard Hamiltonian 46 studies.…”

Section: A Kcufmentioning

confidence: 99%

Ab initiostudy of magnetic interactions inKCuF3andK2
Moreira
¹
,
Illas
²

1999
Phys. Rev. B
32
0
5
0
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The ab initio cluster model approach has been used to study the electronic structure and magnetic coupling of KCuF 3 and K 2 CuF 4 in their various ordered polytype crystal forms. Due to a cooperative Jahn-Teller distortion these systems exhibit strong anisotropies. In particular, the magnetic properties strongly differ from those of isomorphic compounds. Hence, KCuF 3 is a quasi-one-dimensional ͑1D͒ nearest neighbor Heisenberg antiferromagnet whereas K 2 CuF 4 is the only ferromagnet among the K 2 M F 4 series of compounds ͑M ϭMn, Fe, Co, Ni, and Cu͒ behaving all as quasi-2D nearest neighbor Heisenberg systems. Different ab initio techniques are used to explore the magnetic coupling in these systems. All methods, including unrestricted Hartree-Fock, are able to explain the magnetic ordering. However, quantitative agreement with experiment is reached only when using a state-of-the-art configuration interaction approach. Finally, an analysis of the dependence of the magnetic coupling constant with respect to distortion parameters is presented. ͓S0163-1829͑99͒09831-8͔

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Investigations of Two-Dimensional Ferromagnet K₂CuF₄ by Neutron Scattering

Cited by 127 publications

References 27 publications

Quasi-two-dimensional Bose-Einstein condensation of lattice bosons in the spin- 12 XXZ ferromagnet K2CuF4

Quasi-two-dimensional Bose-Einstein condensation of lattice bosons in the spin- 12 XXZ ferromagnet K2CuF4

Ferromagnetic two-dimensional crystals: Single layers of K2CuF4

Ab initiostudy of magnetic interactions inKCuF3andK2
Moreira
¹
,
Illas
²

1999
Phys. Rev. B
32
0
5
0
View full text Add to dashboard Cite

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Investigations of Two-Dimensional Ferromagnet K2CuF4 by Neutron Scattering

Cited by 127 publications

References 27 publications

Quasi-two-dimensional Bose-Einstein condensation of lattice bosons in the spin- 12 XXZ ferromagnet K2CuF4

Quasi-two-dimensional Bose-Einstein condensation of lattice bosons in the spin- 12 XXZ ferromagnet K2CuF4

Ferromagnetic two-dimensional crystals: Single layers of K2CuF4

Ab initiostudy of magnetic interactions inKCuF3andK2Moreira1, Illas2 1999Phys. Rev. B32050View full textAdd to dashboardCite

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Investigations of Two-Dimensional Ferromagnet K₂CuF₄ by Neutron Scattering

Ab initiostudy of magnetic interactions inKCuF3andK2
Moreira
¹
,
Illas
²

1999
Phys. Rev. B
32
0
5
0
View full text Add to dashboard Cite