Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userObservation of spin current in quantum spin liquid
298
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Spin liquid is a state of electron spins in which quantum fluctuation breaks magnetic ordering while maintaining spin correlation. It has been a central topic in magnetism because of its relevance to high-Tc superconductivity and topological states. However, utilizing spin liquid has been quite difficult. Typical spin liquid states are realized in one-dimensional spin systems, called quantum spin chains. Here, we show that a spin liquid in a spin-1/2 quantum chain generates and carries spin current via its long-range spin fluctuation. This is demonstrated by observing an anisotropic negative spin Seebeck effect along the spin chains in Sr2CuO3. The results show that spin current can flow even in an atomic channel owing the spin liquid state, which can be used for atomic spin-current wiring.
rate research
Read More
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.
Cs2CuCl4 is known to possess a quantum spin liquid phase with antiferromagnetic interaction below 2.8 K. We report the observation of a new metastable magnetic phase of the triangular frustrated quantum spin system Cs2CuCl4 induced by the application of hydrostatic pressure. We measured the magnetic properties of Cs2CuCl4 following the application and release of pressure after 3 days. We observed a previously unknown ordered magnetic phase with a transition temperature of 9 K. Furthermore, the recovered sample with new magnetic ground state possesses an equivalent crystal structure to the uncompressed one with antiferromagnetic quantum spin liquid phase.
When magnetic order is suppressed by frustrated interactions, spins form a highly correlated fluctuating spin liquid state down to low temperatures. Magnetic order of local moments can also be suppressed when they are fully screened by conduction electrons through the Kondo effect. Thus, the combination of strong geometrical frustration and Kondo screening may lead to novel types of quantum phase transitions. We report low-temperature thermodynamic measurements on the frustrated Kondo lattice Pr$_2$Ir$_2$O$_7$, which displays a chiral spin liquid state below 1.5 K due to the frustrated interaction between Ising 4f local moments and their interplay with Ir conduction electrons. Our results provide a first clear example of zero-field quantum critical scaling that emerges in a spin liquid state of a highly frustrated metal.
Quantum spin liquids have been at the forefront of correlated electron research ever since their original proposal in 1973, and the realization that they belong to the broader class of intrinsic topological orders, along with the fractional quantum Hall states. According to received wisdom, quantum spin liquids can arise in frustrated magnets with low spin $S$, where strong quantum fluctuations act to destabilize conventional, magnetically ordered states. Here we present a magnet that has a $Z_2$ quantum spin liquid ground state already in the semiclassical, large-$S$ limit. The state has both topological and symmetry related ground state degeneracy, and two types of gaps, a `magnetic flux gap that scales linearly with $S$ and an `electric charge gap that drops exponentially in $S$. The magnet is described by the spin-$S$ version of the spin-1/2 Kitaev honeycomb model, which has been the subject of intense studies in correlated electron systems with strong spin-orbit coupling, and in optical lattice realizations with ultracold atoms. The results apply to both integer and half-integer spins.
We report a neutron scattering study of the spin-1/2 alternating bond antiferromagnet Cu(NO_3)_2. 2.5D_2O for 0.06<k_BT/J_1<1.5. For k_BT/J_1 << 1 the excitation spectrum is dominated by a coherent singlet-triplet mode centered at J_1=0.442(2) meV with sinusoidal dispersion and a bandwidth of J_2=0.106(2) meV. A complete description of the zero temperature contribution to the scattering function from this mode is provided by the Single Mode Approximation. At finite temperatures we observe exponentially activated band narrowing and damping. The relaxation rate is thermally activated and wave vector dependent with the period icity of the reciprocal lattice.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
