Origin of the anomalously low Raman exponents in single molecule magnets

The Raman exponent of single molecular magnetic relaxation may take various unexpected values because of rich phonon spectra and spin-phonon coupling of molecular crystals. We systematically examine the origins of different abnormalities and clarify misunderstandings of the past, particularly the appropriateness of the fitting procedures for the exponents. We find that exponential laws raised by optical phonons can yield spurious power laws with low exponents. This observation indicates long-standing misunderstandings of the origins of low Raman exponents in a large bulk of single molecule magnets. Resulting from spin-lattice coupling with optical modes, the presence of these exponents suggests the importance of the local dynamical environment for the magnetic relaxation in this regime.

Automated summary

This study systematically examines the origins of different abnormalities in the Raman exponents of single molecular magnetic relaxation, clarifying past misunderstandings and the appropriateness of fitting procedures. It is found that exponential laws raised by optical phonons can yield spurious power laws with low exponents, indicating long-standing misunderstandings of the origins of low Raman exponents. The presence of these exponents suggests the importance of the local dynamical environment for magnetic relaxation in this regime, resulting from spin-lattice coupling with optical modes.