35 research outputs found
Microwave Spectroscopy
Contains research objectives and reports on two research projects.U.S. Army Signal Corps under Contract DA36-039-sc-87376Lincoln Laboratory, Purchase Order DDL B-00306U. S. ArmyU. S. NavyU. S. Air Force under Air Force Contract AF19(604)-740
First-principles study of the electrooptic effect in ferroelectric oxides
We present a method to compute the electrooptic tensor from first principles,
explicitly taking into account the electronic, ionic and piezoelectric
contributions. It allows us to study the non-linear optic behavior of three
ferroelectric ABO_3 compounds : LiNbO_3, BaTiO_3 and PbTiO_3. Our calculations
reveal the dominant contribution of the soft mode to the electrooptic
coefficients in LiNbO_3 and BaTiO_3 and identify the coupling between the
electric field and the polar atomic displacements along the B-O chains as the
origin of the large electrooptic response in these compounds.Comment: accepted for publication in Phys. Rev. Let
Microwave Spectroscopy
Contains reports on four research projects.United States Army Signal Corps (Contract DA36-039-sc-87376)Lincoln Laboratory (Purchase Order DDL B-00368)United States ArmyUnited States NavyUnited States Air Force (Contract AF19(604)-7400
First-principles design and subsequent synthesis of a material to search for the permanent electric dipole moment of the electron
We describe the first-principles design and subsequent synthesis of a new
material with the specific functionalities required for a solid-state-based
search for the permanent electric dipole moment of the electron. We show
computationally that perovskite-structure europium barium titanate should
exhibit the required large and pressure-dependent ferroelectric polarization,
local magnetic moments, and absence of magnetic ordering even at liquid helium
temperature. Subsequent synthesis and characterization of
EuBaTiO ceramics confirm the predicted desirable
properties.Comment: Nature Materials, in pres