Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 84: Scanning Probe Techniques: Method Developments
O 84.1: Hauptvortrag
Donnerstag, 10. März 2016, 15:00–15:30, S054
Radio frequency STM on molecular resonators — •Stefan Müllegger — Johannes Kepler University Linz, Institute of Semiconductor and Solid State Physics, Linz, Austria.
To benefit from both, the superior spatial resolution of scanning tunneling microscopy (STM) and the exceptional energy resolution of magnetic resonance techniques, we developed a spectroscopic radio frequency (rf) STM system [1,2]. It enables the detection [1] and excitation [2] of mechanical vibrations of a new type of nano-mechanical resonator system based on one-dimensional chains of only 4 to 7 weakly coupled small molecules on a Au(111) surface. Rf-STM reveals concerted mechanical oscillations at 51–127 MHz with a chain-length dependence in reasonable agreement with a coupled-oscillator model. Moreover, I discuss the resonant excitation of single nuclear (I) and electronic (J) spins by rf tunneling in individual molecular quantum dots by a novel technique denoted as rf scanning tunneling spectroscopy (rf-STS) [3], enabling single-spin spectroscopy unbound from electromagnetic dipole selection rules [4]. Our rf-STS experiments on magnetic molecular quantum dots have revealed nuclear and electronic spin transitions of individual quantum spins of up to Δ Iz=±3 and Δ Jz=±12 with sub-nanometer spatial resolution. The molecular quantum dots are formed by molecules of the single-molecule magnet bis-phthalocyanato terbium (III) on Au(111) at 5 K.
[1] Phys. Rev. Lett. 112, 117201 (2014). [2] Nanotechn. 25, 135705 (2014). [3] Phys. Rev. Lett. 113, 133001 (2014). [4] arXiv:1510.04804.