Effect of Uniaxial Pressure on Structural and Magnetic Phase Transitions in Electron-Doped Iron Pnictides

FCMP Lecture (LIVE!)

 

Date: Thursday, Nov. 12

Time: 3:10 pm

Place: SST 106

 

Speaker: Prof. Pengcheng Dai, Rice University

 

Title:  Effect of Uniaxial Pressure on Structural and Magnetic Phase Transitions in Electron-Doped Iron Pnictides

 

Abstract:  We use neutron resonance spin echo and Larmor diffraction to study the effect of uniaxial pressure on the tetragonal-to-orthorhombic structural (Ts) and antiferromagnetic (AF) phase transitions in iron pnictides

BaFe2−xNixAs2 (x = 0, 0.03, 0.12), SrFe1.97Ni0.03As2, and BaFe2(As0.7P0.3)2. In antiferromagnetically ordered

BaFe2&minus;xNixAs2 and SrFe1.97Ni0.03As2 with TN and Ts (TN <= Ts), a uniaxial pressure necessary to detwin the sample also increases TN, smears out the structural transition, and induces an orthorhombic lattice distortion at all temperatures. In addition, the static AF order induces a magnetoelastic distortion of the average lattice d spacing ($\Delta$ d) in the paramagnetic tetragonal phase that decays in the Curie-Weiss fashion and increases with increasing uniaxial pressure.  By comparing temperature and doping dependence of the pressure induced lattice parameter changes with the elastoresistance and nematic susceptibility obtained from transport and ultrasonic measurements, we conclude that the in-plane resistivity anisotropy found in the paramagnetic state of electron underdoped iron pnictides depends sensitively on the nature of the magnetic phase transition and a strong coupling between the uniaxial pressure induced lattice distortion and electronic nematic susceptibility.

When?

Thu, Nov. 12, 2015
3:10 p.m. - 4:15 p.m.
(GMT-0500) US/Central

Where?

Space Science Room 106
Space Science and Technology Bldg - Rice University
Houston, Texas 77005
United States