Magnetoresistance of ''handmade'' dimers

Spin-orbit coupling links spin and momentum degrees of freedom by the Hamiltonian H = ξLS (L, S: orbital momentum and spin operators, ξ: coupling strength). It is the origin of phenomena such as magnetocrystalline anisotropy and anisotropic magnetoresistance, which are of fundamental interest and important for sensor applications. To tune spin-orbit coupling at a single atom, the high rotational symmetry of the atom should be reduced. Johannes Schöneberg, Alexander Weismann and Richard Berndt achieved this by constructing dimers from single Pb atoms on an Fe double layer substrate, whose domain pattern exhibits suitable magnetization directions. First-principles calculations by Paolo Ferriani and Stefan Heinze reveal the molecular orbitals that cause the large observed anisotropic magnetoresistance. The results are published in Physical Review B "Tunneling anisotropic magnetoresistance via molecular Pi orbitals of Pb dimers" and have been highlighted by an Editors' suggestion for papers that the editors and referees find of particular interest, importance, or clarity.