Effects of exchange and weak Dzyaloshinsky-Moriya anisotropies on thermodynamic characteristics of spin-gapped magnets

Rakhimov, Abdulla; Khudoyberdiev, Asliddin; Tanatar, Bilal

doi:10.48550/arxiv.1909.13641

Cited by 3 publications

(5 citation statements)

References 44 publications

(87 reference statements)

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“…Unfortunately, the present simple approach cannot describe saturation effects, since they are not included in the starting effective Hamiltonian (14) properly. Besides, for simplicity anisotropic effects, which are essential [10,11,14] for TlCuCl 3 due to Dzyaloshinsky -Moriya (DM) or exchange anisotropy (EA) interactions are neglected. Nevertheless, our predictions on the inversion temperature are in a good qualitative agreement with the existing experimental observations.…”

Section: Discussionmentioning

confidence: 99%

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Joule-Thomson temperature of a triplon system of dimerized quantum magnets

2020

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Exploiting the analogy between ultracold atomic gases and the system of triplons, we study magneto-thermodynamic properties of dimerized quantum magnets in the framework of Bose -Einstein condensation (BEC). Particularly, introducing the inversion (or Joule -Thomson) temperature T JT as the point where Joule -Thomson coefficient of an isenthalpic process changes its sign, we show that for a simple paramagnet, this temperature is infinite, while for three-dimensional (3D) dimerized quantum magnets it is finite and always larger than the critical temperature T c of BEC. Below the inversion temperature T < T JT the system of triplons may be in a liquid phase, which undergoes a transition into a superfluid phase at T ≤ T c < T JT . The dependence of the inversion temperature on the external magnetic field T JT (H) has been calculated for quantum magnets of TlCuCl 3 and Sr 3 Cr 2 O 8 .

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Section: Discussionmentioning

confidence: 99%

“…in TlCuCl 3 , this symmetry can be explicitly broken due to anisotropy. As a result, instead of a phase transition one has to deal with a crossover where the staggered magnetization is renormalized [10][11][12][13][14]. In the present work, for simplicity, we shall neglect such effects and exploit Eqs.…”

Section: Introductionmentioning

confidence: 99%

Joule-Thomson temperature of a triplon system of dimerized quantum magnets

2020

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“…This is in good agreement with our predicted temperature dependence of derivatives of the contact: (∂C/∂H) has a maximum and (∂C/∂T) changes its sign near the phase transition from BEC to a normal phase. On the other hand, it is well established that the heat capacity C V has a cusp near the transition point [49][50][51][52]. Therefore, we ask whether the quantities under consideration have a jump near T c .…”

Section: Contact and Its Derivatives Near Critical Temperaturementioning

confidence: 98%

Critical behavior of Tan’s contact for bosonic systems with a fixed chemical potential

Rakhimov¹,

Abdurakhmonov²,

Tanatar³

2021

J. Phys.: Condens. Matter

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The temperature dependence of Tan's contact parameter C and its derivatives for spin gapped quantum magnets are investigated. We use the paradigm of Bose-Einstein condensation (BEC) to describe the low temperature properties of quasiparticles in the system known as triplons. Since the number of particles and the condensate fraction are not fixed we use the μVT ensemble to calculate the thermodynamic quantities. The interactions are treated at the Hartree-Fock-Bogoliubov approximation level. We obtained the temperature dependence of C and its derivative with respect to temperature and applied magnetic field both above and below T c of the phase transition from the normal phase to BEC. We have shown that C is regular, while its derivatives are discontinuous at T c in accordance with Ehrenfest's classification of phase transitions. Moreover, we have found a sign change in ∂C/∂T close to the critical temperature. As to the quantum critical point, C and its derivatives are regular as a function of the control parameter r, which induces the quantum phase transition. At very low temperatures, one may evaluate C simply from the expression C = m 2 μ 2 /ā 4 , where the only parameter effective mass of quasiparticles should be estimated. We propose a method for measuring of Tan's contact for spin gapped dimerized magnets.

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“…0 , 0 0 , 5 The magnetizations M (T ) per dimer. Note that for better description of experimental data on M (T ) effects of anisotropies [43], which have been neglected here, should be included.…”

Section: Tan's Contact For a Triplon Gasmentioning

confidence: 99%

“…On the other hand, it is well established that the heat capacity C V has a cusp near the transition point [43,[46][47][48]. Therefore, we ask whether the quantities under consideration have a jump near T c .…”

Section: Contact and Its Derivatives Near Critical Temperaturementioning

confidence: 99%

Critical behavior of Tan's contact for bosonic systems with a fixed chemical potential

Rakhimov,

Abdurakhmonov,

Tanatar

2021

Preprint

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The temperature dependence of Tan's contact parameter C and its derivatives for spin gapped quantum magnets are investigated. We use the paradigm of Bose-Einstein condensation (BEC) to describe the low temperature properties of quasiparticles in the system known as triplons. Since the number of particles and the condensate fraction are not fixed we use the µV T ensemble to calculate the thermodynamic quantities. The interactions are treated at the Hartree-Fock-Bogoliubov approximation level. We obtained the temperature dependence of C and its derivative with respect to temperature and applied magnetic field both above and below the critical temperature T c of the phase transition from the normal phase to BEC. We have shown that C is regular, while its derivatives are discontinuous at T c in accordance with Ehrenfest's classification of phase transitions. Moreover, we have found a sign change in ∂C/∂T close to the critical temperature. As to the quantum critical point, C and its derivatives are regular as a function of the control parameter r, which induces the quantum phase transition. At very low temperatures, one may evaluate C simply from the expression C = m 2 µ 2 /ā 4 , where the only parameter effective mass of quasiparticles should be estimated. We propose a method for experimentallly measuring of Tan's contact for spin gapped dimerized magnets.

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Effects of exchange and weak Dzyaloshinsky-Moriya anisotropies on thermodynamic characteristics of spin-gapped magnets

Cited by 3 publications

References 44 publications

Joule-Thomson temperature of a triplon system of dimerized quantum magnets

Joule-Thomson temperature of a triplon system of dimerized quantum magnets

Critical behavior of Tan’s contact for bosonic systems with a fixed chemical potential

Critical behavior of Tan's contact for bosonic systems with a fixed chemical potential

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