arXiv subjects

F. Tijiwa Birk

Publications and source records attributed to F. Tijiwa Birk.

2 recordsLinked to original sources

arXiv2012

Magnetic instability induced by tunnel current in single Co nanoparticles

Measurements of magnetic hysteresis loops in single Co nanoparticles at dilution refrigerator temperatures are presented. The nanoparticles are in electric contact with bulk Al leads via tunnel junctions. The tunnel current versus magnetic field displays a magnetic hysteresis loop. The magnetic switching field is reduced by current, and the magnetization of the nanoparticle can be switched by applying a voltage pulse, demonstrating that the magnetic stability of the nanoparticle is diminished by electron transport. Additional transitions and random switches of magnetization can be driven by large currents.

cond-mat.mes-hall↗

arXiv2011

Microwave coupled electron tunneling measurement of Co nanoparticles

We study electron tunneling through Co nanoparticles in the presence of repeated microwave pulses at 4.2K. While individual pulses are too weak to affect the magnetic switching field, repeated microwave pulses start to reduce the magnetic switching field at 10μs spacing. We use I-V curve as a thermometer to show that the microwave pulses do not heat the sample, showing that magnetization in Co nanoparticles is directly excited by microwave pulses, and the relaxation time of the excitation energy is in the range of microsecond.

cond-mat.mes-hall↗