Effects of pressure on the electronic and structural properties of LaOFeAs

摘要

We studied the pressure effects on the electronic and structural properties of LaOFeAs by first-principles calculations. For the antiferromagnetic (AFM) phase with stripelike aligned Fe spins, the electronic density of states at the Fermi level [N(E_F)] slightly descends first with increasing applied pressure, then bounces up with further increasing pressure (or decreasing volume), and reaches its maximum at ～29.2 GPa with the volume -80% of the ambient pressure value (V_0). Similar behavior is expected in the physical quantities that are proportional to N(E_F), such as the electronic specific heat and the Pauli paramagnetic susceptibility. At this volume (V=0.8 V_0), the LaOFeAs crystal undergoes a structural phase transition from the orthorhombic structure to the tetragonal one, which is accompanied by the disappearance of the long-ranged AFM order.