Heat capacity study of BaFe2As2 : Effects of annealing
Abstract
Heat capacity, x-ray diffraction, and resistivity measurements on a high-quality BaFe2As2 sample show an evolution of the magnetostructural transition with successive annealing periods. After a 30-day anneal the resistivity in the (ab) plane decreases by more than an order of magnitude, to 12μΩcm , with a residual resistance ratio ∼36 ; the heat capacity anomaly at the transition sharpens, to an overall width of less than K, and shifts from 135.4 to 140.2 K. The heat capacity anomaly in both the as-grown sample and after the 30-day anneal shows a hysteresis of ∼0.15K , and is unchanged in a magnetic field μ0H=14T . The x-ray and heat capacity data combined suggest that there is a first-order jump in the structural order parameter. The entropy of the transition is reported.
- Publication:
-
Physical Review B
- Pub Date:
- October 2010
- DOI:
- 10.1103/PhysRevB.82.144525
- arXiv:
- arXiv:1008.2967
- Bibcode:
- 2010PhRvB..82n4525R
- Keywords:
-
- 74.25.Dw;
- 74.25.Ha;
- 74.70.-b;
- Superconductivity phase diagrams;
- Magnetic properties;
- Superconducting materials;
- Condensed Matter - Superconductivity;
- Condensed Matter - Strongly Correlated Electrons
- E-Print:
- Physical Review B 82, 144525, 2010