In-plane uniaxial pressure-induced out-of-plane antiferromagnetic moment and critical fluctuations in BaFe2As2

Abstract

A small in-plane external uniaxial pressure has been widely used as an effective method to acquire single domain iron pnictide BaFe2As2, which exhibits twin-domains without uniaxial strain below the tetragonal-to-orthorhombic structural (nematic) transition temperature Ts. Although it is generally assumed that such a pressure will not affect the intrinsic electronic/magnetic properties of the system, it is known to enhance the antiferromagnetic (AF) ordering temperature TN ( < Ts) and create in-plane resistivity anisotropy above Ts. Here we use neutron polarization analysis to show that such a strain on BaFe2As2 also induces a static or quasi-static out-of-plane (c-axis) AF order and its associated critical spin fluctuations near TN/Ts. Therefore, uniaxial pressure necessary to detwin single crystals of BaFe2As2 actually rotates the easy axis of the collinear AF order near TN/Ts, and such effects due to spin-orbit coupling must be taken into account to unveil the intrinsic electronic/magnetic properties of the system.

Preferred Spin Excitations in the Bilayer Iron-Based Superconductor CaK(Fe0.96Ni0.04)4Liu1, Bourgès2, Sidis3 et al. 2022Phys. Rev. Lett.Self Cite12130View full textAdd to dashboardCite

“…By tuning η from zero to finite, the degenerated region between the SVC and SSDW phases (or between the SVC and CSDW phases) increases, then the magnetic phase may easily transform to another under the assistance of SOC [15]. This explains the competition between SSDW and CSDW in the hole-underdoped compounds [9,10] as well as the additional c-axis moments induced by uniaxial pressure in the parent compound BaFe 2 As 2 [74].…”

Single-domain stripe order in a high-temperature superconductor

“…1b). We note that other neutron scattering experiments under uniaxial pressure have been performed in earlier pioneering studies [61][62][63][64] . The small ordered moment in La 1.88 Sr 0.12 CuO 4 65 required us to construct a strain cell made of high purity aluminium with an open geometry to minimize background contributions.…”

Nematic Fluctuations in the Non-Superconducting Iron Pnictide BaFe1.9−xNi0.1CrxAs2

“…After that, the crystals were cut into rectangle shapes (typical sizes: 1 mm × 2 mm) by a wire saw under the directions [1, 0, 0] × [0, 1, 0] in orthorhombic lattice notation (a = b = 5.6 Å). By applying a uniaxial pressure around 10 MPa, the crystal can be fully detwinned at low temperature, where the direction of pressure was defined as the b direction, and the pressure-free direction was defined as the a direction [60][61][62][63][96][97][98][99]. The in-plane resistivity (ρ a,b ) was measured by the standard four-probe method with the Physical Property Measurement System (PPMS) from Quantum Design.…”