Magnetic anisotropy in 5d transition metal–porphyrin molecules*

Single molecule magnets (SMMs) with large magnetic anisotropy energy (MAE) have great potential applications in magnetic recording. Using the first-principles calculations, we investigate the MAE of 5d transition metal–porphyrin-based SMMs by using the PBE and PBE + U with different U values, respectively. The results indicate that W–P, Re–P, Os–P, and Ir–P possess the considerably large MAE among 5d TM–P SMMs. Furthermore, the MAE of 5d TM–P can be facilely manipulated by tensile strain. The reduction of the absolute value of MAE for Ir–P molecule caused by tensile strain makes it easier to implement the writing operation. The decreasing of the occupation number of minority-spin channels of Ir-d x 2 – y 2 orbital leads the MAE to decrease when the tensile strain increases.