# Phase Diagram and Spin Hamiltonian of Weakly-coupled Anisotropic S=1/2 Chains in CuCl _{2} ^{.}2((CD _{3}) _{2}SO)

## Abstract

Field-dependent specific heat and neutron scattering measurements were used to explore the antiferromagnetic S=(1/2) chain compound CuCl{sub 2}{center_dot}2((CD{sub 3}){sub 2}SO). At zero field the system acquires magnetic long-range order below T{sub N}=0.93 K with an ordered moment of 0.44{micro}{sub B}. An external field along the b axis strengthens the zero-field magnetic order, while fields along the a and c axes lead to a collapse of the exchange stabilized order at {micro}{sub 0}H{sub c}=6 T and {micro}{sub 0}H{sub c}=4 T (extrapolated to zero temperature) and the formation of an energy gap in the excitation spectrum. We relate the field-induced gap to the presence of a staggered g-tensor and Dzyaloshinskii-Moriya interactions, which lead to effective staggered fields for magnetic fields applied along the a and c axes. Competition between anisotropy, interchain interactions, and staggered fields leads to a succession of three phases as a function of field applied along the c axis. For fields greater than {micro}{sub 0}H{sub c}, we find a magnetic structure that reflects the symmetry of the staggered fields. The critical exponent, beta, of the temperature driven phase transitions are indistinguishable from those of the three-dimensional Heisenberg magnet, while measurements for transitions driven by quantum fluctuations produce larger valuesmore »

- Authors:

- Johns Hopkins University
- ORNL
- Los Alamos National Laboratory (LANL)
- Brookhaven National Laboratory (BNL)

- Publication Date:

- Research Org.:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); High Flux Isotope Reactor

- Sponsoring Org.:
- USDOE Office of Science (SC)

- OSTI Identifier:
- 931971

- DOE Contract Number:
- DE-AC05-00OR22725

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Physical Review B; Journal Volume: 75

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ANISOTROPY; CHAINS; ENERGY GAP; EXCITATION; FLUCTUATIONS; HAMILTONIANS; MAGNETIC FIELDS; NEUTRONS; PHASE DIAGRAMS; SCATTERING; SPECIFIC HEAT; SPIN; SYMMETRY

### Citation Formats

```
Chen, Y., Stone, Matthew B, Kenzelmann, M., Batista, C. D., Reich, D. H., and Broholm, C. L.
```*Phase Diagram and Spin Hamiltonian of Weakly-coupled Anisotropic S=1/2 Chains in CuCl2.2((CD3)2SO)*. United States: N. p., 2007.
Web. doi:10.1103/PhysRevB.75.214409.

```
Chen, Y., Stone, Matthew B, Kenzelmann, M., Batista, C. D., Reich, D. H., & Broholm, C. L.
```*Phase Diagram and Spin Hamiltonian of Weakly-coupled Anisotropic S=1/2 Chains in CuCl2.2((CD3)2SO)*. United States. doi:10.1103/PhysRevB.75.214409.

```
Chen, Y., Stone, Matthew B, Kenzelmann, M., Batista, C. D., Reich, D. H., and Broholm, C. L. Mon .
"Phase Diagram and Spin Hamiltonian of Weakly-coupled Anisotropic S=1/2 Chains in CuCl2.2((CD3)2SO)". United States.
doi:10.1103/PhysRevB.75.214409.
```

```
@article{osti_931971,
```

title = {Phase Diagram and Spin Hamiltonian of Weakly-coupled Anisotropic S=1/2 Chains in CuCl2.2((CD3)2SO)},

author = {Chen, Y. and Stone, Matthew B and Kenzelmann, M. and Batista, C. D. and Reich, D. H. and Broholm, C. L.},

abstractNote = {Field-dependent specific heat and neutron scattering measurements were used to explore the antiferromagnetic S=(1/2) chain compound CuCl{sub 2}{center_dot}2((CD{sub 3}){sub 2}SO). At zero field the system acquires magnetic long-range order below T{sub N}=0.93 K with an ordered moment of 0.44{micro}{sub B}. An external field along the b axis strengthens the zero-field magnetic order, while fields along the a and c axes lead to a collapse of the exchange stabilized order at {micro}{sub 0}H{sub c}=6 T and {micro}{sub 0}H{sub c}=4 T (extrapolated to zero temperature) and the formation of an energy gap in the excitation spectrum. We relate the field-induced gap to the presence of a staggered g-tensor and Dzyaloshinskii-Moriya interactions, which lead to effective staggered fields for magnetic fields applied along the a and c axes. Competition between anisotropy, interchain interactions, and staggered fields leads to a succession of three phases as a function of field applied along the c axis. For fields greater than {micro}{sub 0}H{sub c}, we find a magnetic structure that reflects the symmetry of the staggered fields. The critical exponent, beta, of the temperature driven phase transitions are indistinguishable from those of the three-dimensional Heisenberg magnet, while measurements for transitions driven by quantum fluctuations produce larger values of beta.},

doi = {10.1103/PhysRevB.75.214409},

journal = {Physical Review B},

number = ,

volume = 75,

place = {United States},

year = {Mon Jan 01 00:00:00 EST 2007},

month = {Mon Jan 01 00:00:00 EST 2007}

}