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Agarmani Y, Hartmann S, Zimmermann J, Gati E, Delleske C, Tutsch U, Wolf B, Lang M. Advanced technique for measuring relative length changes under control of temperature and helium-gas pressure. Rev Sci Instrum 2022; 93:113902. [PMID: 36461492 DOI: 10.1063/5.0099412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 09/28/2022] [Indexed: 06/17/2023]
Abstract
We report the realization of an advanced technique for measuring relative length changes ΔL/L of mm-sized samples under the control of temperature (T) and helium-gas pressure (P). The system, which is an extension of the apparatus described in the work of Manna et al. [Rev. Sci. Instrum. 83, 085111 (2012)], consists of two 4He-bath cryostats, each of which houses a pressure cell and a capacitive dilatometer. The interconnection of the pressure cells, the temperature of which can be controlled individually, opens up various modes of operation to perform measurements of ΔL/L under the variation of temperature and pressure. Special features of this apparatus include the possibility (1) to increase the pressure to values far in excess of the external pressure reservoir, (2) to substantially improve the pressure stability during temperature sweeps, (3) to enable continuous pressure sweeps with both decreasing and increasing pressure, and (4) to simultaneously measure the dielectric constant of the pressure-transmitting medium, viz., helium, εr He(T,P), along the same T-P trajectory as that used for taking the ΔL(T, P)/L data. The performance of the setup is demonstrated by measurements of relative length changes (ΔL/L)T at T = 180 K of single crystalline NaCl upon continuously varying the pressure in the range 6 ≤ P ≤ 40 MPa.
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Affiliation(s)
- Y Agarmani
- Institute of Physics, Goethe University Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
| | - S Hartmann
- Institute of Physics, Goethe University Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
| | - J Zimmermann
- Institute of Physics, Goethe University Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
| | - E Gati
- Institute of Physics, Goethe University Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
| | - C Delleske
- Institute of Physics, Goethe University Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
| | - U Tutsch
- Institute of Physics, Goethe University Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
| | - B Wolf
- Institute of Physics, Goethe University Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
| | - M Lang
- Institute of Physics, Goethe University Frankfurt, Max-von-Laue-Straße 1, 60438 Frankfurt am Main, Germany
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Tutsch U, Tsyplyatyev O, Kuhnt M, Postulka L, Wolf B, Cong PT, Ritter F, Krellner C, Aßmus W, Schmidt B, Thalmeier P, Kopietz P, Lang M. Specific Heat Study of 1D and 2D Excitations in the Layered Frustrated Quantum Antiferromagnets Cs_{2}CuCl_{4-x}Br_{x}. Phys Rev Lett 2019; 123:147202. [PMID: 31702204 DOI: 10.1103/physrevlett.123.147202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 05/30/2019] [Indexed: 06/10/2023]
Abstract
We report an experimental and theoretical study of the low-temperature specific heat C and magnetic susceptibility χ of the layered anisotropic triangular-lattice spin-1/2 Heisenberg antiferromagnets Cs_{2}CuCl_{4-x}Br_{x} with x=0, 1, 2, and 4. We find that the ratio J^{'}/J of the exchange couplings ranges from 0.32 to ≈0.78, implying a change (crossover or quantum phase transition) in the materials' magnetic properties from one-dimensional (1D) behavior for J^{'}/J<0.6 to two-dimensional (2D) behavior for J^{'}/J≈0.78. For J^{'}/J<0.6, realized for x=0, 1, and 4, we find a magnetic contribution to the low-temperature specific heat, C_{m}∝T, consistent with spinon excitations in 1D spin-1/2 Heisenberg antiferromagnets. Remarkably, for x=2, where J^{'}/J≈0.78 implies a 2D magnetic character, we also observe C_{m}∝T. This finding, which contrasts the prediction of C_{m}∝T^{2} made by standard spin-wave theories, shows that Fermi-like statistics also plays a significant role for the magnetic excitations in spin-1/2 frustrated 2D antiferromagnets.
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Affiliation(s)
- U Tutsch
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - O Tsyplyatyev
- Institut für Theoretische Physik, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - M Kuhnt
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - L Postulka
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - B Wolf
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - P T Cong
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - F Ritter
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - C Krellner
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - W Aßmus
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - B Schmidt
- Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany
| | - P Thalmeier
- Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany
| | - P Kopietz
- Institut für Theoretische Physik, Goethe-Universität, 60438 Frankfurt (M), Germany
| | - M Lang
- Physikalisches Institut, Goethe-Universität, 60438 Frankfurt (M), Germany
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Cong PT, Wolf B, Tutsch U, Remović-Langer K, Schreuer J, Süllow S, Lang M. Ultrasonic investigation on the distorted diamond chain compound Azurite. ACTA ACUST UNITED AC 2010. [DOI: 10.1088/1742-6596/200/1/012226] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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