Anisotropic exchange in linear chain complexes of copper(II)

McGregor, Kenneth T.; Soos, Z. G.

doi:10.1063/1.432500

Cited by 66 publications

(38 citation statements)

References 41 publications

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“…Among other possible processes, dipolar broadening is expected to be the main cause of broadening in our sample (11). Dipolar broadening is usually described in terms of the second moment which is written as the sum of three contributions (13,14), the first one, usually called secular, being…”

Section: Figmentioning

confidence: 99%

DPPH as a Standard for High-Field EPR

Krzystek

Sienkiewicz

Pardi

et al. 1997

Journal of Magnetic Resonance

103

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Section: Figmentioning

confidence: 99%

DPPH as a Standard for High-Field EPR

Krzystek

Sienkiewicz

Pardi

et al. 1997

Journal of Magnetic Resonance

103

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“…This material has a relatively small exchange constant J /k B = 10.3 K along the chain direction (crystallographic a axis of an orthorhombic structure) [27], which results in a laboratory-accessible saturation field H s = 2J /gμ B 13.9-15 T depending on the field orientation [28][29][30]. Its ground state is a Tomonaga-Luttinger liquid (TLL) for H < H s and a saturated ferromagnet with a gap for H > H s , leaving a QCP at H = H s (see Fig.…”

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confidence: 99%

Quantum critical scaling for a Heisenberg spin-12chain around saturation

Jeong

Rønnow

2015

Phys. Rev. B

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We demonstrate quantum critical scaling for an S = 1/2 Heisenberg antiferromagnetic chain compound Cu(C 4 H 4 N 2 )(NO 3 ) 2 in a magnetic field around saturation, by analyzing previously reported magnetization [Y. Kono et al., Phys. Rev. Lett. 114, 037202 (2015)], thermal expansion [J. Rohrkamp et al., J. Phys.: Conf. Ser. 200, 012169 (2010)], and NMR relaxation data [H. Kühne et al., Phys. Rev. B 80, 045110 (2009)]. The scaling of magnetization is demonstrated through collapsing the data for a range of both temperature and field onto a single curve without making any assumption for a theoretical form. The data collapse is subsequently shown to closely follow the theoretically predicted scaling function without any adjustable parameters. Experimental boundaries for the quantum critical region could be drawn from the variable range beyond which the scaled data deviate from the theoretical function. Similarly to the magnetization, quantum critical scaling of the thermal expansion is also demonstrated. Further, the spin dynamics probed via NMR relaxation rate 1/T 1 close to the saturation is shown to follow the theoretically predicted quantum critical behavior as 1/T 1 ∝ T −0.5 persisting up to temperatures as high as k B T J , where J is the exchange coupling constant. A quantum critical point (QCP) is a zero-temperature singularity in the phase diagram of matter forming the border between two competing ground states [1]. It is driven by a nonthermal parameter such as a magnetic field, pressure, or chemical substitution, and characterized by strong quantum fluctuations. While a QCP is defined strictly at zero temperature, the interplay between quantum and thermal fluctuations gives rise to a so-called quantum critical region at finite temperatures in an extended parameter space (illustrated by the yellow fan-out area in Fig. 1). This intriguing region is characterized by the absence of energy scales other than temperature as well as the corresponding critical properties of physical observables, e.g., correlation or response functions, which culminate into scaling behavior and universality [1][2][3][4]. Such quantum criticality has been experimentally observed or inferred in diverse systems including magnetic insulators [5][6][7], organic conductors [8], heavy fermions [9,10], cuprates [11], pnictides [12], and cold atoms [13], and is widely believed to underpin exotic phenomena like unconventional superconductivity. However, understanding quantum criticality through connecting microscopics to experimental observation largely remains challenging [1,[8][9][10][11][12]14].Quantum magnets are an ideal playground in that respect owing to their simple and well-defined Hamiltonian [15]. In particular, one-dimensional (1D) spin systems for which exact solutions are available may serve as a test bed for quantitative comparison between theories and experiments [16][17][18][19]. Indeed, quite a few excellent quasi-1D quantum magnets having accessible critical field strength, i.e., relatively small exchange coupling strengt...

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“…If the g tensor coincides with the dipolar tensor, we expect a (3 cos 20-1) dependence in that plane. The dipolar second moments have been calculated for KCuC13 and NH4CuC13 using the crystal structure data, following the method of McGregor and Soos [23]. The angular variation of the calculated second moments is shown in figure 4, while the values are collected in table 4.…”

Section: Resultsmentioning

confidence: 99%

Study of exchange and dipolar interaction in MCuX₃systems by E.P.R.

Harish

1985

Molecular Physics

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To cite this article: S.P. Harish (1985) Study of exchange and dipolar interaction in MCuX 3 systems by E.P.R., Molecular Physics, 54:4, 911-925, Compounds of the ABX 3 type (where A = K, NH4, Cs, Rb, B = Cu, Ni, Cr, X = C1, Br, F, I) make an interesting study by the presence of BX6, B 2 X4, B 3 X9, linear chains which also show interesting magnetic properties and crystal structures. Single crystals of KCuC13 , NH4CuC13 , RbCuC13 and CsCuC13, in the polycrystalline state have been studied by E.P.R. measurements. These compounds show simple E.P.R. spectra but have interesting dependences of line widths on temperature and g values. The line width dependence has been shown to arise from unresolved hyperfine and dipolar interactions, confirmed by second moment calculations. The quasi axial nature of the g value has been explained as being due to antiferro-distortive ordering of the Cu 2X6 z-octahedra. The ammonium ion acts as a better exchange pathway than potassium in the two respective crystals. The E.P.R. intensities have a Curie type dependence and has no contribution from the dimeric coppers.

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Anisotropic exchange in linear chain complexes of copper(II)

Cited by 66 publications

References 41 publications

DPPH as a Standard for High-Field EPR

DPPH as a Standard for High-Field EPR

Quantum critical scaling for a Heisenberg spin-12chain around saturation

Study of exchange and dipolar interaction in MCuX₃systems by E.P.R.

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Anisotropic exchange in linear chain complexes of copper(II)

Cited by 66 publications

References 41 publications

DPPH as a Standard for High-Field EPR

DPPH as a Standard for High-Field EPR

Quantum critical scaling for a Heisenberg spin-12chain around saturation

Study of exchange and dipolar interaction in MCuX3systems by E.P.R.

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Study of exchange and dipolar interaction in MCuX₃systems by E.P.R.