Low Dimensional Magnets

Rice, T. M.

doi:10.1007/3-540-45649-x_5

“…1 Such systems comprise both one-(chains and ladders), as well as two-dimensional (triangular-, square-, and rectangular) spin arrangements, which can be realized by synthesizing the relevant materials. These can serve as playgrounds for testing key theoretical concepts, such as those of quantum phase transitions and criticality.…”

Section: Introductionmentioning

confidence: 99%

Pressure and magnetic field effects on a quasi-two-dimensional spin-12Heisenberg antiferromagnet

Barbero

¹

,

Shiroka

²

,

Landee

³

et al. 2016

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Cu(pz) 2 (ClO 4 ) 2 (with pz denoting pyrazine, C 4 H 4 N 2 ) is among the best realizations of a two-dimensional spin-1 /2 square-lattice antiferromagnet. Below T N = 4.21 K, its weak interlayer couplings induce a 3D magnetic order, strongly influenced by external magnetic fields and/or hydrostatic pressure. Previous work, focusing on the [H, T ] phase diagram, identified a spin-flop transition, resulting in a field-tunable bicritical point. However, the influence of external pressure has not been investigated yet. Here we explore the extended [p, H, T ] phase diagram of Cu(pz) 2 (ClO 4 ) 2 under pressures up to 12 kbar and magnetic fields up to 7.1 T, via magnetometry and 35 Cl nuclear magnetic resonance (NMR) measurements. The application of magnetic fields enhances T X Y , the crossover temperature from the Heisenberg to the X Y model, thus pointing to an enhancement of the effective anisotropy. The applied pressure has an opposite effect [dT N /dp = −0.050(8) K/kbar], as it modifies marginally the interlayer couplings, but likely changes more significantly the orbital reorientation and the square-lattice deformation. This results in a remodeling of the effective Hamiltonian, whereby the field and pressure effects compensate each other. Finally, by comparing the experimental data with numerical simulations we estimate T BKT , the temperature of the Berezinskii-Kosterlitz-Thouless topological transition and argue why it is inaccessible in our case.

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“…Although no complete review of the subject exists so far, different aspects are summarized e.g. in [1][2][3][4][5]. In this paper we will illustrate the status of the field by pointing out and presenting selected recent and new results.…”

Section: Introductionmentioning

confidence: 99%

Magnetization plateaus in frustrated antiferromagnetic quantum spin models

Honecker¹,

Schulenburg²,

Richter³

2004

J. Phys.: Condens. Matter

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Plateaus can be observed in the zero-temperature magnetization curve of quantum spin systems at rational values of the magnetization. In one dimension, the appearance of a plateau is controlled by a quantization condition for the magnetization which involves the length of the local spin and the volume of a translational unit cell of the ground state. We discuss examples of geometrically frustrated quantum spin systems with large (in general unbounded) periodicities of spontaneous breaking of translational symmetry in the ground state.In two dimensions, we discuss the square, triangular and Kagomé lattices using exact diagonalization (ED) for up to N = 40 sites. For the spin-1/2 XXZ model on the triangular lattice we study the nature and stability region of a plateau at one third of the saturation magnetization. The Kagomé lattice gives rise to particularly rich behaviour with several plateaus in the magnetization curve and a jump due to local magnon excitations just below saturation.

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“…The antiferromagnetic coupling of magnetic moments in materials with low-dimensional sub-units gives rise to interesting phenomena, including the Haldane gap, the quantum spin-liquid state, topological phase transitions, etc. 1 Such systems comprise both one-(chains and ladders), as well as two-dimensional (triangular-, square-, and rectangular) spin arrangements, which can be realized by synthesizing the relevant materials. These can serve as playgrounds for testing key theoretical concepts, such as those of quantum phase transitions and criticality.…”

Section: Introductionmentioning

confidence: 99%

Pressure and magnetic field effects on a quasi-2D spin-1/2 Heisenberg antiferromagnet

Barbero,

Shiroka,

Landee

et al. 2016

Preprint

0

View full text Add to dashboard Cite

Cu(pz) 2 (ClO 4 ) 2 (with pz denoting pyrazine, C 4 H 4 N 2 ) is among the best realizations of a two-dimensional spin-1 /2 square-lattice antiferromagnet. Below T N = 4.21 K, its weak interlayer couplings induce a 3D magnetic order, strongly influenced by external magnetic fields and/or hydrostatic pressure. Previous work, focusing on the [H, T ] phase diagram, identified a spin-flop transition, resulting in a field-tunable bicritical point. However, the influence of external pressure has not been investigated yet. Here we explore the extended [p, H, T ] phase diagram of Cu(pz) 2 (ClO 4 ) 2 under pressures up to 12 kbar and magnetic fields up to 7.1 T, via magnetometry and 35 Cl nuclear magnetic resonance (NMR) measurements. The application of magnetic fields enhances T X Y , the crossover temperature from the Heisenberg to the X Y model, thus pointing to an enhancement of the effective anisotropy. The applied pressure has an opposite effect [dT N /dp = −0.050(8) K/kbar], as it modifies marginally the interlayer couplings, but likely changes more significantly the orbital reorientation and the square-lattice deformation. This results in a remodeling of the effective Hamiltonian, whereby the field and pressure effects compensate each other. Finally, by comparing the experimental data with numerical simulations we estimate T BKT , the temperature of the Berezinskii-Kosterlitz-Thouless topological transition and argue why it is inaccessible in our case.

show abstract

Low Dimensional Magnets

Cited by 4 publications

References 37 publications

Pressure and magnetic field effects on a quasi-two-dimensional spin-12Heisenberg antiferromagnet

Pressure and magnetic field effects on a quasi-two-dimensional spin-12Heisenberg antiferromagnet

Magnetization plateaus in frustrated antiferromagnetic quantum spin models

Pressure and magnetic field effects on a quasi-2D spin-1/2 Heisenberg antiferromagnet

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