Spin and charge dynamics in [TbPc${}_2$]${}^0$ and [DyPc${}_2$]${}^0$ single molecule magnets

Abstract

Magnetization, AC susceptibility and $\mu$SR measurements have been performed in neutral phthalocyaninato lanthanide ([LnPc${}_2{]}^0$) single molecule magnets in order to determine the low-energy levels structure and to compare the low-frequency spin excitations probed by means of macroscopic techniques, such as AC susceptibility, with the ones explored by means of techniques of microscopic character, such as $\mu$SR. Both techniques show a high temperature thermally activated regime for the spin dynamics and a low temperature tunneling one. While in the activated regime the correlation times for the spin fluctuations estimated by AC susceptibility and $\mu$SR basically agree, clear discrepancies are found in the tunneling regime. In particular, $\mu$SR probes a faster dynamics with respect to AC susceptibility. It is argued that the tunneling dynamics probed by $\mu$SR involves fluctuations which do not yield a net change in the macroscopic magnetization probed by AC susceptibiliy. Finally resistivity measurements in [TbPc${}_2{]}^0$ crystals show a high temperature nearly metallic behaviour and a low temperature activated behaviour.

8 pages, 12 figures

References in corpus (2)

• Spin dynamics in rare earth single molecule magnets from muSR and NMR in [TbPc${}_2$]${}^0$ and [DyPc${}_2$]${}^0$
• Strong electronic correlations in Li${}_x$ZnPc organic metals

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• Lanthanide-radical magnetic coupling in [LnPc${}_2$]${}^0$: Competing exchange mechanisms captured via ab initio multi-reference calculations
• NMR and ${\mu }^{+}$SR detection of unconventional spin dynamics in Er(trensal) and Dy(trensal) molecular magnets
• Persistence of slow dynamics in Tb(OETAP)${}_2$ single molecule magnets embedded in conducting polymers