相关论文: Pnictides as frustrated quantum antiferromagnet cl…

We consider a two-band superconductor with relative phase $\pi $ between the two order parameters as a model for the superconducting state in ferropnictides. Within this model we calculate the microwave response and the NMR relaxation rate.…

The recently discovered Fe-pnictide and chalcogenide superconductors display low-temperature properties suggesting superconducting gap structures which appear to vary substantially from family to family, and even within families as a…

We develop an analytical theory for generic disorder-driven quantum phase transitions. We apply this formalism to the superconductor-insulator transition and we briefly discuss the applications to the order-disorder transition in quantum…

Superconductivity in the iron pnictides and chalcogenides is closely connected to a bad-metal normal state and a nearby antiferromagnetic order. Therefore, considerable attention has been focused on the role of electron correlations and…

Quantum phase transitions occur at zero temperature upon variation of some nonthermal control parameters. The Ising chain in a transverse field is probably the most-studied model undergoing such a transition, from ferromagnetic to…

We present a quantum transport theory for generic magnetic metals, in which magnetism occurs predominantly due to exchange interactions, such as ferromagnets, antiferromagnets, altermagnets and p-wave magnets. Our theory is valid both for…

We report on isofield magnetization curves obtained as a function of temperature in two single crystals of $Ba_{1-x}K_xFe_2As_2$ with superconducting transition temperature $T_c$=28K and 32.7 K. Results obtained for fields above 20 kOe show…

Investigation of materials that exhibit quantum phase transition provides valuable insights into fundamental problems in physics. We present neutron scattering under pressure in a triangular-lattice antiferromagnet which has a quantum…

We have developed the quasi-classical formalism for a self-induced vortex state in ferromagnetic superconductors. By combining the spatially averaged approximation of the superconductivity with the phenomenological form of the…

The interplay between the structural and magnetic phase transitions occurring in the Fe-based pnictide superconductors is studied within a Ginzburg-Landau approach. We show that the magnetoelastic coupling between the corresponding order…

We report the effect of applied pressures on magnetic and superconducting order in single crystals of the aliovalent La-doped iron pnictide material Ca$_{1-x}$La$_{x}$Fe$_{2}$As$_{2}$. Using electrical transport, elastic neutron scattering…

Quantum critical (QC) phenomena can be accessed by studying quantum magnets under an applied magnetic field ($B$). The QC points are located at the endpoints of magnetization plateaus and separate gapped and gapless phases. In one…

We explore if the phase separation or coexistence of the spin density wave (SDW) and superconductivity (SC) states has any relation to the incommensurability of the SDW in the Fe pnictide superconductors. A systematic method of determining…

We study a unified mechanism for spin-density-wave (SDW) and superconductivity in a minimal model, in which itinerant electrons and local moments coexist as previously proposed for the iron pnictides [EPL, 88, 17010 (2009)]. The phase…

We examine electronic states of antiferromagnetic phase in iron pnictides by mean-field calculations of the optical conductivity. We find that a five-band model exhibiting a small magnetic moment, inconsistent with the first-principles…

We measured the pressure dependence of in-plane resistivity $\rho_{ab}$ in the recently-discovered iron-based superconductor Ca$_{10}$(Ir$_{4}$As$_{8}$)(Fe$_{2-x}$Ir$_{x}$As$_{2}$)$_{5}$, which shows a unique structural phase transition in…

Iron-based superconductors have been found to exhibit an intimate interplay of orbital, spin, and lattice degrees of freedom, dramatically affecting their low-energy electronic properties, including superconductivity. Albeit the precise…

Recently discovered superconducting P-doped EuFe$_2$As$_2$ compounds reveal the situation when the superconducting critical temperature substantially exceeds the ferromagnetic transition temperature. The main mechanism of the interplay…

The phenomenology of the iron pnictide superconductor can be described by the threeband s+- Eliashberg theory in which the mechanism of superconducting coupling is mediated by antiferromagnetic spin fluctuations and whose characteristic…

One of the central questions about the iron pnictides concerns the extent to which their electrons are strongly correlated. Here we address this issue through the phenomenology of the charge transport and dynamics, single-electron…