Related papers: Chiral order and electromagnetic dynamics in one-d…
The entangled charge and spin dynamics in strongly electron correlated system has been a fruitful playground for exploring new physical phenomena. Here with resonant inelastic X-ray scattering we studied the spin dynamics of SrIrO$_3$, a…
A microscopic magnetic model for the spin-1/2 Heisenberg chain compound CuSe2O5 is developed based on the results of a joint experimental and theoretical study. Magnetic susceptibility and specific heat data give evidence for quasi-1D…
A frustrated spin-$1/2$ XXZ chain model comprising a ferromagnetic nearest-neighbor coupling with the bond alternation, $J_1(1\pm\delta)<0$, and an antiferromagnetic second-neighbor exchange coupling $J_2>0$ is studied at zero and weak…
We report on the microscopic model of the recently synthesized one-dimensional quantum magnet (NO)Cu(NO3)3. Applying density functional theory band structure calculations, we obtain a leading antiferromagnetic exchange coupling J ~ 200 K,…
The influence of bond randomness on long range magnetic ordering in the weakly coupled S = 1/2 antiferromagnetic spin chain materials Cu(py)2(Cl1-xBrx)2 is studied by muon spin rotation and bulk measurements. Disorder is found to have a…
Motivated by experiments on ultracold atoms which have realized the Haldane model for a Chern insulator, we consider its strongly correlated Mott limit with spin-$1/2$ fermions. We find that slave rotor mean field theory yields gapped or…
We present an investigation of magnetic ordering in the two-dimensional S=1/2 quantum magnet Cu(Pz)_2(ClO_4)_2 using specific heat and zero field muon-spin relaxation (\mu^+SR). The magnetic contribution to the specific heat is consistent…
The origin of non-collinear magnetic order in UO$_{2}$ is studied by an ab initio dynamical-mean-field-theory framework in conjunction with a linear-response approach for evaluating inter-site superexchange interactions between U 5$f^{2}$…
The phase diagram of the quasi-one-dimensional magnet NaCuMoO$_4$(OH) is established through single-crystal NMR and heat-capacity measurements. The $^{23}$Na and $^1$H NMR experiments indicate a spiral and a collinear spin-density-wave…
We study the magnetic properties of two types of one dimensional XX spin 1/2 chains. The first type has only nearest neighbor interactions which can be either antiferromagnetic or ferromagnetic and the second type which has both nearest…
We present a combined experimental and theoretical study of the spin-1/2 compound CuP$_2$O$_6$ that features a network of two-dimensional (2D) antiferromagnetic (AFM) square planes, interconnected via one-dimensional (1D) AFM spin chains.…
For the 1D-frustrated ferromagnetic J_1-J_2 model with interchain coupling added, we analyze the dynamical and static structure factor S(k,omega), the pitch angle phi of the magnetic structure, the magnetization curve of edge-shared chain…
This thesis deals with the Hubbard model as prototypical model to describe the physics of electrons in the two-dimensional copper-oxide planes of high-$T_c$ cuprates. To get approximate solutions, we employ functional renormalization group…
The square lattice spin-1/2 antiferromagnet containing a dilute concentration, $\delta$, of randomly placed ferromagnetic nearest-neighbor bonds is studied at low-temperature via non-linear $\sigma$-model techniques and by exact…
We consider the class of quantum spin chains with arbitrary $U_q(\mathfrak{sl}_2)$-invariant nearest neighbor interactions, sometimes called $\textrm{SU}_q(2)$ for the quantum deformation of $\textrm{SU}(2)$, for $q>0$. We derive sufficient…
In general, quantum fluctuations are suppressed in ferromagnetic materials because they admit a simple unfrustrated ground state, greatly limiting the scope of phenomena that can be observed in these materials. In this work, we show how…
We report measurements on Ti$_4$MnBi$_2$, where a crystal structure involving linear chains of Mn ions suggests one-dimensional magnetic character. The electrical resistivity is metallic, consistent with the results of electronic structure…
Here by combining a symmetry-based analysis with numerical computations we predict a new kind of magnetic ordering - antichiral ferromagnetism. The relationship between chiral and antichiral magnetic order is conceptually similar to the…
In chiral ferromagnets, weak spin-orbit interactions twist the ferromagnetic order into spirals, leading to helical order. We investigate an extended Ginzburg-Landau theory of such systems where the helical order is destabilized in favor of…
We report structural and magnetic properties of the spin-$\frac12$ quantum antiferromagnet Cu[C$_6$H$_2$(COO)$_4$][C$_2$H$_5$NH$_3$]$_2$ by means of single-crystal x-ray diffraction, magnetization, heat capacity, and electron spin resonance…