SKM 2023 – scientific programme
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O: Fachverband Oberflächenphysik
O 15: Spins on Surfaces at the Atomic Scale II
O 15.3: Talk
Monday, March 27, 2023, 15:30–15:45, REC C 213
Quantum coherence of single atomic S = 1/2 spins on ultra-thin insulating layers — Hong Bui1,2, We-Hyo Seo1,2, Yu Wang1,2, Andreas Heinrich1,2, and •Soo-Hyon Phark1,2 — 1Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, Korea — 2Department of Physics, Ewha Womans Universtiy, Seoul 03760, Korea
A scanning tunneling microscope (STM), when combined with electron spin resonance (ESR), provides a solid-state platform of atomic scale spin qubit. However, its quantum coherence is considerably limited by couplings with metallic substrate and tunneling electrons. Here we report a study on the quantum coherence of single Ti atomic spins (S = 1/2) on two- (2ML) and three- (3ML) monolayer-thick MgO on Ag(100) using pulsed-ESR equipped in a STM at 0.4 K. We were able to drive the coherent rotations of the spin on the 3ML-MgO with a Rabi rate (Ω) up to 100 MHz, which is an order faster than that on the 2ML-MgO. Coherence time (T2) from Hahn-echo measurement revealed the role of the tunneling electrons, resetting the state of a Ti spin with a probability of 0.15/electron, which is the same for Ti spins on both 2ML- and 3ML-MgO. Of more interesting is the zero current T2 of 2 microsec on 3ML-MgO, about 5 times longer than that on 2ML-MgO, emphasizing the importance of decoupling the spin from the metallic substrate as well as tunneling electrons. Such considerable improvements in Ω and T2 are promising for high fidelity quantum gate operations to a Ti spin qubit, further brightening a way to raise the on-surface spin qubits on a stage of the quantum-coherent applications.