Magnetic measurements on micrometer-sized samples under high pressure using designed NV centers.

Pressure can be used to tune the interplay among structural, electronic, and magnetic interactions in materials. High pressures are usually applied in the diamond anvil cell, making it difficult to study the magnetic properties of a micrometer-sized sample. We report a method for spatially resolved optical magnetometry based on imaging a layer of nitrogen-vacancy (NV) centers created at the surface of a diamond anvil.

Melting Curve and Liquid Structure of Nitrogen Probed by X-ray Diffraction to 120 GPa.

Synchrotron x-ray diffraction measurements of nitrogen are performed up to 120 GPa to determine the melting curve and the structural changes of the solid and liquid phases along it. The melting temperature exhibits a monotonic increase up to the triple point where the epsilon molecular solid, the cubic gauche covalent solid, and the fluid meet at 116 GPa, 2080 K. Above, the stability of the cubic gauche phase induces a sharp increase of the melting curve.

(N(2))(6)Ne(7): A high pressure van der Waals insertion compound.

The binary phase diagram of N(2)-Ne mixtures has been measured at 296 K by visual observation and Raman spectroscopy. The topology of the phase diagram points to the existence of the stoichiometric compound N(2))(6)Ne(7). Its structure has been solved by single-crystal synchrotron x-ray diffraction.

Multiphoton magnetooptical trap.

We demonstrate a magnetooptical trap (MOT) configuration which employs optical forces due to light scattering between electronically excited states of the atom. With the standard MOT laser beams propagating along the x and y directions, the laser beams along the z direction are at a different wavelength that couples two sets of excited states. We demonstrate efficient cooling and trapping of cesium atoms in a vapor cell and sub-Doppler cooling on both the red and blue sides of the two-photon resonance.