Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userSpin dynamics in Heisenberg triangular antiferromagnets: A muSR study of LiCrO2
130
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We report a muSR study of LiCrO2, which has a magnetic lattice made up of a stacking of triangular Heisenberg antiferromagnetic (Cr3+, S = 3/2) layers. A static magnetically ordered state is observed below the transition temperature T_N = 62 K, while the expected peak of the relaxation rate is slightly shifted downward by a few kelvins below T_N. We draw a comparison with the isostructural compound NaCrO2, where an exotic broad fluctuating regime has been observed [A. Olariu, P. Mendels, F. Bert, B. G. Ueland, P. Schiffer, R. F. Berger, and R. J. Cava, Phys. Rev. Lett. 97, 167203 (2006)] and was suggested to originate from topological excitations of the triangular lattice. Replacing Na by Li strongly narrows the exotic fluctuating regime formerly observed in NaCrO2, which we attribute to a more pronounced inter-plane coupling in LiCrO2.
rate research
Read More
We show that the mesoscopic incommensurate $mathbb{Z}_2$ vortex crystals proposed for layered triangular anisotropic magnets can be most saliently identified by two distinctive signatures in dynamical spin response experiments: The presence of pseudo-Goldstone `phonon modes at low frequencies $omega$, associated with the collective vibrations of the vortex cores, and a characteristic multi-scattered intensity profile at higher $omega$, arising from a large number of Bragg reflections and magnon bandgaps. These are direct fingerprints of the large vortex sizes and magnetic unit cells and the solitonic spin profile around the vortex cores.
Motivated by various spin-1/2 compounds like Cs$_2$CuCl$_4$ or $kappa$-(BEDT-TTF)$_2$Cu$_2$(CN)$_3$, we derive a Raman-scattering operator {it `a la} Shastry and Shraiman for various geometries. For T=0, the exact spectra is computed by Lanczos algorithm for finite-size clusters. We perform a systematic investigation as a function of $J_2/J_1$, the exchange constant ratio: ranging from $J_2=0$, the well known square-lattice case, to $J_2/J_1=1$ the isotropic triangular lattice. We discuss the polarization dependence of the spectra and show how it can be used to detect precursors of the instabilities of the ground state against quantum fluctuations.
The cradle of quantum spin liquids, triangular antiferromagnets show strong proclivity to magnetic order and require deliberate tuning to stabilize a spin-liquid state. In this brief review, we juxtapose recent theoretical developments that trace the parameter regime of the spin-liquid phase, with experimental results for Co-based and Yb-based triangular antiferromagnets. Unconventional spin dynamics arising from both ordered and disordered ground states is discussed, and the notion of a geometrically perfect triangular system is scrutinized to demonstrate non-trivial imperfections that may assist magnetic frustration in stabilizing dynamic spin states with peculiar excitations.
The correlated spin dynamics and the temperature dependence of the correlation length $xi(T)$ in two-dimensional quantum ($S=1/2$) Heisenberg antiferromagnets (2DQHAF) on square lattice are discussed in the light of experimental results of proton spin lattice relaxation in copper formiate tetradeuterate (CFTD). In this compound the exchange constant is much smaller than the one in recently studied 2DQHAF, such as La$_2$CuO$_4$ and Sr$_2$CuO$_2$Cl$_2$. Thus the spin dynamics can be probed in detail over a wider temperature range. The NMR relaxation rates turn out in excellent agreement with a theoretical mode-coupling calculation. The deduced temperature behavior of $xi(T)$ is in agreement with high-temperature expansions, quantum Monte Carlo simulations and the pure quantum self-consistent harmonic approximation. Contrary to the predictions of the theories based on the Non-Linear $sigma$ Model, no evidence of crossover between different quantum regimes is observed.
We report magnetization, specific heat, muon spin rotation and Na NMR measurements on the S=3/2 rhombohedrally stacked Heisenberg antiferromagnet NaCrO2. This compound appears to be an ideal candidate for the study of triangular Heisenberg antiferromagnets with very weak interlayer coupling. While specific heat and magnetization measurements indicate the occurrence of a transition in the range 40-46 K, both muon spin rotation and NMR reveal a fluctuating regime extending well below T_c, with a peak of relaxation rate 1/T1 around 30 K. This novel finding is discussed within the context of excitations in the triangular Heisenberg antiferromagnets.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
