Origin of the anomalously low Raman exponents in single molecule magnets
Lei Gu, Ruqian Wu
Abstract
The Raman exponent of single-molecular magnetic relaxation may take various\nunexpected values because of rich phonon spectrum and spin-phonon coupling of\nmolecular crystals. We systematically examine the origins of different\nabnormalities, and clarify misunderstandings in the past, particularly the\nappropriateness of the fitting procedures for the exponents. We find that\nexponential laws raised by optical phonons can yield spurious power laws with\nlow exponents. This observation indicates long-standing misunderstandings for\norigins of low Raman exponents in a large bulk of single-molecule magnets.\nResulting from spin-lattice coupling with optical modes, presence of these\nexponents suggests the importance of the local dynamical environment for the\nmagnetic relaxation in this regime.