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_x²-y² orbital leads the MAE to decrease when the tensile strain increases.