The search for topological states in strongly correlated electron systems has renewed the interest in the Kondo insulator SmB6. One of the most intriguing previous results was an anomalous electron spin resonance spectrum in Gd-doped SmB6. This spectrum was attributed to Gd2+ ions because it could be very well decribed by a model considering a change in the valence from Gd3+ to Gd2+, a dynamic Jahn-Teller effect and a 4f7 5d1 ground state in the Hamiltonian. In our work, we have revisited this scenario using electron spin resonance and energy dispersive X-ray spectroscopy measurements. Our results suggest that the resonance is produced by Gd2+ ions; however the resonance stems from an extrinsic oxide impurity phase that lies on the surface of the crystal.
Effects of La non-magnetic impurities on the spin resonance of CeCoIn$_{5}$
用中子非弹性散射研究了La非磁性杂质对CeCoIn $_{5}$自旋动力学的影响。在La取代的系统中，自旋共振峰（在纯系统中在$Ω_{res}=0.55 meV$处观察到）向较低能量移动，但比率$Ω_{res}/k_{B}T_{c}$保持不变。激励加宽，直到它达到0.3 meV等于在正常状态下的准弹性信号的值。La取代的演变与Ni和Zn取代的YBa $_{2}$ Cu $_{3}$ O $_{7}$的磁共振的演变进行了比较。
Direct determination of the crystal field parameters of Dy, Er and Yb impurities in the skutterudite compound CeFe$_{4}$P$_{12}$ by Electron Spin Resonance
尽管在过去的十年里对方钴矿进行了广泛的研究，但它们的电晶体场基态仍然是一个有争议的问题。我们表明，电子自旋共振（ESR）测量可以确定完整的晶场参数（CFPs）的Th立方对称性（Im 3）的Ce $_{1-x}$ R $_{x}$ Fe $_{4}$ P $_{12}$（R = Dy，Er，Yb，$x\lesssim 0.003$）方钴矿化合物。根据ESR数据的分析，确定了Ce $^{3+}$位点上这些稀土中的每一种的三个CFPs，B4c，B6c和B6t。场和温度依赖性的掺杂晶体的测量磁化强度是在一个很好的协议与来自ESR的CFPs Bnm预测。
In this work we analyze the nonequilibrium transport through a quantum impurity (quantum dot or molecule) attached to ferromagnetic leads by using a hybrid numerical renormalization group-time-dependent density matrix renormalization group thermofield quench approach.For this, we study the bias dependence of the differential conductance through the system, which shows a finite zero-bias peak, characteristic of the Kondo resonance and reminiscent of the equilibrium local density of states. In the non-equilibrium settings, the resonance in the differential conductance is also found to decrease w…
Bound states, resonances, and their thermodynamic properties in pseudospin-1 systems with short-range impurities
Faculty of Physics, Kyiv National Taras Shevchenko University（基辅国立塔拉斯舍甫琴科大学物理系）；Bogolyubov Institute for Theoretical Physics（博戈留博夫理论物理研究所）；Department of Physics and Astronomy, University of Missouri（密苏里大学物理与天文学系）；MU Materials Science & Engineering Institute, University of Missouri（密苏里大学材料科学与工程研究所）
Quantum spin liquids (QSLs) are highly entangled, disordered magnetic states that arise in frustrated Mott insulators and host exotic fractional excitations such as spinons and chargons. Despite being charge insulators some QSLs are predicted to exhibit gapless itinerant spinons that yield metallic behavior in the spin channel. We have deposited isolated magnetic atoms onto single-layer (SL) 1T-TaSe$_2$, a gapless QSL candidate, to experimentally probe how itinerant spinons couple to impurity spin centers. Using scanning tunneling spectroscopy we observe the emergence of new, impurity-induced …
Quantum spin-liquids are strongly correlated phases of matter displaying a highly entangled ground state. Due to their unconventional nature, finding experimental signatures of these states has proven to be a remarkable challenge. Here we show that the effects of local impurities can provide strong signatures of a Dirac quantum spin-liquid state. Focusing on a gapless Dirac quantum spin-liquid state as realized in NaYbO$_2$, we show that single magnetic impurity coupled to the quantum spin-liquid state creates a resonant spinon peak at zero frequency, coexisting the original Dirac spinons. We …
Revealing altermagnetic Fermi surfaces with two Kondo impurities
New Cornerstone Science Laboratory, Department of Physics, School of Science, Westlake University（西湖大学理学院物理系新 cornerstone 科学实验室）；Institute for Theoretical Solid State Physics, IFW Dresden（德累斯顿工业大学IFW理论固体物理研究所）；Würzburg-Dresden Cluster of Excellence ctd.qmat（维尔茨堡-德累斯顿卓越集群ctd.qmat）；Institut für Theoretische Physik und Astrophysik, Universität Würzburg（维尔茨堡大学理论与天体物理研究所）；Institute for Theoretical Sciences, Westlake University（西湖大学理论科学研究院）；Key Laboratory for Quantum Materials of Zhejiang Province, School of Science, Westlake University（西湖大学理学院浙江省量子材料重点实验室）；Institute of Natural Sciences, Westlake Institute for Advanced Study（西湖高等研究院自然科学研究院）
Magnetic impurities with sufficient anisotropy could account for the observed strong deviation of the edge conductance of 2D topological insulators from the anticipated quantized value. In this work we consider such a helical edge coupled to dilute impurities with an arbitrary spin $S$ and a general form of the exchange matrix. We calculate the backscattering current noise at finite frequencies as a function of the temperature and applied voltage bias. We find that in addition to the Lorentzian resonance at zero frequency, the backscattering current noise features Fano-type resonances at non-z…
Revisiting the chain magnetism in Sr14Cu24O41: Experimental and numerical results
通过测量电子自旋共振（ESR）和在高达14 T的磁场下的静态磁化强度M，研究了Sr_（14）Cu_（24）O_（41）中空穴掺杂的CuO_2自旋链的磁性.在该化合物中，二聚的基态和链中的电荷顺序被很好地建立。我们的实验数据表明，在低温下的居里样增加的M以及相关的ESR信号的发生是由于少量的顺磁中心，这不是外在的缺陷，而是不成对的铜自旋链。这些观察定性地证实了最近的从头计算的基态性能的CuO 2链在Sr 14 Cu 24 O 41。我们的互补量子统计模拟结果的磁化强度的温度和场的依赖性可以很好地描述了一个有效的海森堡模型，其中的基态配置是由自旋二聚体，三聚体，和单体。
We study the spin-polarized spectral properties of Yu-Shiba-Rusinov resonance states induced by magnetic impurities in 2- and 3-dimensional nematic superconductors: few layer Bi$_2$Te$_3$ grown on FeTe$_{0.55}$Se$_{0.45}$ (2-dimensional) and Cu$_x$Bi$_2$Se$_3$ (3-dimensional). We focus on the relationship between pairing symmetry and the topograph of spin-polarized spectroscopy. We calculate the spin-polarized local density of states (SP LDOS) and the corresponding Fourier transformation using the $T$-matrix method for both the 2- and 3-dimensional materials. Various situations with different …
The cubic double perovskite Ba$_2$YIrO$_6$ has been investigated by the local probe techniques nuclear magnetic resonance ($^{89}$Y NMR) and muon spin rotation (muSR). Both methods confirm the absence of magnetic long-range order in this compound but find evidence for diluted localized paramagnetic moments. NMR spin-lattice relaxation rate 1/T1 measurements suggest a slowing down of localized spin moments at low temperatures. An increase of the muSR spin-lattice relaxation rate lambda confirms the presence of weak magnetism in Ba$_2$YIrO$_6$ . However, these findings cannot be explained by the…
The S=1/2 Heisenberg spin chain compound SrCuO2 doped with different amounts of nickel (Ni), palladium (Pd), zinc (Zn) and cobalt (Co) has been studied by means of Cu nuclear magnetic resonance (NMR). Replacing only a few of the S=1/2 Cu ions with Ni, Pd, Zn or Co has a major impact on the magnetic properties of the spin chain system. In the case of Ni, Pd and Zn an unusual line broadening in the low temperature NMR spectra reveals the existence of an impurity-induced local alternating magnetization (LAM), while exponentially decaying spin-lattice relaxation rates $T_1^{-1}$ towards low temper…
携带自旋的磁性杂质与主体金属的传导电子自旋的反铁磁耦合是导致诸如Cu ${}_{0.998}$ Fe ${}_{0.002}$的合金在低温下电阻增加的基本机制，如Kondo最初提出的。这种耦合已经成为耦合到连续体的局域电子态的一种非常普遍的性质。在纳米导体中设计人工可控磁性杂质的可能性为研究与初始情况相比不寻常情况下的这种多体现象开辟了一条道路，特别是在失衡情况下。到目前为止，测量的重点是平均电流。在这里，我们报告的\textit{current fluctuations}（噪音）的测量在碳纳米管设备中制造的人工近藤杂质。我们发现一个显着的增强的电流噪声内的近藤共振，在简单的非相互作用的理论相矛盾。我们的研究结果提供了一个测试平台的最重要的凝聚态物质的多体理论在平衡的情况下，揭示了高导电性分子器件的噪声特性。
Hybrid semiconductor-superconductor quantum dot devices are tunable physical realizations of quantum impurity models for a magnetic impurity in a superconducting host. The binding energy of the localized sub-gap Shiba states is set by the gate voltages and external magnetic field. In this work we discuss the effects of the Zeeman spin splitting which is generically present both in the quantum dot and in the (thin-film) superconductor. The unequal $g$-factors in semiconductor and superconductor materials result in respective Zeeman splittings of different magnitude. We consider both classical a…
