Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userFractional Spin fluctuations and quantum liquid signature in Gd2ZnIrO6
133
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Hitherto, the discrete identification of quantum spin liquid phase, holy grail of condensed matter physics, remains a challenging task experimentally. However, the precursor of quantum spin liquid state may reflect in the spin dynamics even in the paramagnetic phase over a wide temperature range as conjectured theoretically. Here we report comprehensive inelastic light (Raman) scattering measurements on the Ir based double perovskite, Gd2ZnIrO6, as a function of different incident photon energies and polarization in a broad temperature range. Our results evidenced the spin fractionalization within the paramagnetic phase reflected in the emergence of a polarization independent quasi-elastic peak at low energies with lowering temperature. Also, the fluctuating scattering amplitude measured via dynamic Raman susceptibility increases with lowering temperature and decreases mildly upon entering into long-range magnetic ordering phase, below 23 K, suggesting the magnetic origin of these fluctuations. This anomalous scattering response is thus indicative of fluctuating fractional spin evincing the quantum spin liquid phase in a three-dimensional double perovskite system.
rate research
Read More
The ground-state ordering and dynamics of the two-dimensional (2D) S=1/2 frustrated Heisenberg antiferromagnet Cs_2CuCl_4 is explored using neutron scattering in high magnetic fields. We find that the dynamic correlations show a highly dispersive continuum of excited states, characteristic of the RVB state, arising from pairs of S=1/2 spinons. Quantum renormalization factors for the excitation energies (1.65) and incommensuration (0.56) are large.
Magnetic structures of organic Mott insulators X[Pd(dmit)2]2 (X=Me4P, Me4Sb), of which electronic states are located near quantum spin liquid (X=EtMe3Sb), are demonstrated by 13C NMR. Antiferromagnetic spectra and nuclear relaxations show two distinct magnetic moments within each Pd(dmit)2 molecule, which cannot be described by single band dimer-Mott model and requires intramolecular electronic correlation. This unconventional fragmentation of S = 1/2 electron spin with strong quantum fluctuation is presumably caused by nearly degenerated intramolecular multiple orbitals, and shares a notion of quantum liquids where electronic excitations are fractionalized and S = 1/2 spin is no longer an elementary particle.
The $S$ = $frac{1}{2}$ kagome Heisenberg antiferromagnet (KHA) is a leading model hosting a quantum spin liquid (QSL), but the exact nature of its ground state remains a key issue under debate. In the previously well-studied candidate materials, magnetic defects always dominate the low-energy spectrum and hinder the detection of the intrinsic nature. We demonstrate that the new single crystal of YCu$_3$[OH(D)]$_{6.5}$Br$_{2.5}$ is a perfect KHA without evident magnetic defects ($ll$ 0.8%). Through fitting the magnetic susceptibilities of the orientated single crystals, we find the spin system with weak anisotropic interactions and with first-, second-, and third-neighbor couplings, $J_1$ $sim$ 56 K and $J_2$ $sim$ $J_3$ $sim$ 0.1$J_1$, belongs to the continuous family of fully frustrated KHAs. No conventional freezing is observed down to 0.36 K $sim$ 0.006$J_1$, and the raw specific heat exhibits a nearly quadratic temperature dependence below 1 K $sim$ 0.02$J_1$, well consistent with a gapless (spin gap $leq$ 0.025$J_1$) Dirac QSL.
Collective behaviour of electrons, frustration induced quantum fluctuations and entanglement in quantum materials underlie some of the emergent quantum phenomena with exotic quasi-particle excitations that are highly relevant for technological applications. Frustrated quantum materials offer an exciting venue to realize highly entangled quantum states with fractional excitations. Herein, we present our thermodynamic and muon spin relaxation measurements on the recently synthesized frustrated antiferromagnet Li4CuTeO6, in which Cu2+ ions (S = 1/2) constitute a disordered triangular-lattice in the crystallographic ab-plane. Our experiments detect neither long-range magnetic ordering nor spin freezing down to a temperature of 1.55 K despite the presence of strong antiferromagnetic interaction between Cu2+ moments leading to a large Curie-Weiss temperature of -163 K. Muon spin relaxation results demonstrate a dynamic liquid-like quantum state. The temperature and magnetic field scaling of magnetization and specific heat reveal a data collapse pointing towards the presence of random-singlets within a disorder-driven correlated and dynamic ground-state in this frustrated antiferromagnet.
This article is an introductory review of the physics of quantum spin liquid (QSL) states. Quantum magnetism is a rapidly evolving field, and recent developments reveal that the ground states and low-energy physics of frustrated spin systems may develop many exotic behaviors once we leave the regime of semi-classical approaches. The purpose of this article is to introduce these developments. The article begins by explaining how semi-classical approaches fail once quantum mechanics become important and then describes the alternative approaches for addressing the problem. We discuss mainly spin $1/2$ systems, and we spend most of our time in this article on one particular set of plausible spin liquid states in which spins are represented by fermions. These states are spin-singlet states and may be viewed as an extension of Fermi liquid states to Mott insulators, and they are usually classified in the category of so-called $SU(2)$, $U(1)$ or $Z_2$ spin liquid states. We review the basic theory regarding these states and the extensions of these states to include the effect of spin-orbit coupling and to higher spin ($S>1/2$) systems. Two other important approaches with strong influences on the understanding of spin liquid states are also introduced: (i) matrix product states and projected entangled pair states and (ii) the Kitaev honeycomb model. Experimental progress concerning spin liquid states in realistic materials, including anisotropic triangular lattice systems ($kappa$-(ET)$_{2}$Cu$_{2}$(CN)$_{3}$ and EtMe$_{3}$Sb[(Pd(dmit)$_{2}$]$_{2}$), kagome lattice systems (ZnCu$_{3}$(OH)$_{6}$Cl$_{2}$) and hyperkagome lattice systems (Na$_{4}$Ir$_{3}$O$_{8}$), is reviewed and compared against the corresponding theories.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
