Effect of Nematic Order on the Low-Energy Spin Fluctuations in Detwinned BaFe1.935Ni0.065As2

Abstract

The origin of nematic order remains one of the major debates in iron-based superconductors. In theories based on spin nematicity, one major prediction is that the spin-spin correlation length at (0,π) should decrease with decreasing temperature below the structural transition temperature T_{s}. Here, we report inelastic neutron scattering studies on the low-energy spin fluctuations in BaFe_{1.935}Ni_{0.065}As_{2} under uniaxial pressure. Both intensity and spin-spin correlation start to show anisotropic behavior at high temperature, while the reduction of the spin-spin correlation length at (0,π) happens just below T_{s}, suggesting the strong effect of nematic order on low-energy spin fluctuations. Our results favor the idea that treats the spin degree of freedom as the driving force of the electronic nematic order.

Anisotropic resonance modes emerging in an antiferromagnetic superconducting state

“…By choosing the scattering vector (0.5, 0.5, l ) in our sample crystal we select a single domain orientation for which the scattering vector constitutes a magnetic zone center, while it is a zone boundary for the other domain. Due to the very high magnon energies of the order of 200 meV, expected at the zone boundary 30 , we may exclude any scattering from the other domain, as it has recently been proven in an experiment on a detwinned crystal 31 .…”

Electronic origin of structural transition in 122 Fe based superconductors

“…A second scenario is that the C 4 symmetry is broken primarily by electronic interactions so that lattice degrees of freedom are secondary order parameters that passively follow the symmetry breaking induced by the electronic interactions hence the primary order parameter is electronic in origin. One such scenario is the spin-nematic transition whereby the spins of the two Fe sublattices phase-lock, this breaks C 4 symmetry, without developing any spontaneous magnetization, i.e., without breaking time reversal symmetry [18][19][20][21][22][23][24][25][26][27][28]. Another possible candidate in this scenario is ferro-orbital ordering [28][29][30][31][32][33], where below nematic transition either the occupations or the hopping matrix elements (or both) of the d xz and the d yz orbitals of Fe become inequivalent.…”

Revealing fermionic quantum criticality from new Monte Carlo techniques

“…In the studies of nFLs, one of the central focuses is systems with itinerant quantum critical points (IQCPs), which have attracted extensive research efforts for nearly half century dating back to the celebrated Hertz-Millis-Moriya (HMM) framework [4][5][6]. In the study of correlated quantum materials, quantum criticality in itinerant electron systems is of great importance and interests [1,[3][4][5][6][7][8][9], and it plays an important role in the understanding of anomalous transport, strange metal and nFL behaviors [10][11][12][13][14] in various quantum materials, such as heavy-fermion materials [2,15], Cu-and Fe-based hightemperature superconductors [16][17][18][19], the recently discovered pressure-driven quantum critical point (QCP) between magnetic order and superconductivity in transition-metal monopnictides, CrAs [20], MnP [21], CrAs 1−x P x [22] and other Cr/Mn-3d electron systems [23] and the more recent discoveries in twisted angle graphene heterostructures [24][25][26]. However, after decades of extensive efforts [1,[3][4][5][6][7][8][9][10][27][28][29]…”