Spin-lattice relaxation via quantum tunneling in diluted crystals of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>Fe</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:math>single-molecule magnets
Physical review. B, Condensed matter and materials physics