Hiroki Morishita

Robust absolute magnetometry with organic thin-film devices

Magnetic field sensors based on organic thin-film materials have attracted considerable interest in recent years as they can be manufactured at very low cost and on flexible substrates. However, the technological relevance of such magnetoresistive sensors is limited owing to their narrow magnetic field ranges (∼30 mT) and the continuous calibration required to compensate temperature fluctuations and material degradation. Conversely, magnetic resonance (MR)-based sensors, which utilize fundamental physical relationships for extremely precise measurements of fields, are usually large and expensive. Here we demonstrate an organic magnetic resonance-based magnetometer, employing spin-dependent electronic transitions in an organic diode, which combines the low-cost thin-film fabrication and integration properties of organic electronics with the precision of a MR-based sensor. We show that the device never requires calibration, operates over large temperature and magnetic field ranges, is robust against materials degradation and allows for absolute sensitivities of <50 nT Hz−1/2.

Perfect selective alignment of nitrogen-vacancy centers in diamond

Nitrogen-vacancy (NV) centers in diamond have attracted significant interest because of their excellent spin and optical characteristics for quantum information and metrology. To take advantage of the characteristics, the precise control of the orientation of the N-V axis in the lattice is essential. Here we show that the orientation of more than 99 % of the NV centers can be aligned along the [111]-axis by CVD homoepitaxial growth on (111)-substrates. We also discuss about mechanisms of the alignment. Our result enables a fourfold improvement in magnetic-field sensitivity and opens new avenues to the optimum design of NV center devices.

Electrical detection and magnetic-field control of spin states in phosphorus-doped silicon

Electron paramagnetic resonance of ensembles of phosphorus donors in silicon has been detected electrically with externally applied magnetic fields lower than 200 G. Because the spin Hamiltonian was dominated by the contact hyperfine term rather than by the Zeeman terms at such low magnetic fields, superposition states

Linewidth of low-field electrically detected magnetic resonance of phosphorus in isotopically controlled silicon

\alpha{}| \uparrow \downarrow >+\beta{}| \downarrow \uparrow >

Tunnel anisotropic magnetoresistance in CoFeB|MgO|Ta junctions

and

Optically detected magnetic resonance of high-density ensemble of NV(-) centers in diamond.

-\beta{}| \uparrow \downarrow > + \alpha{}| \downarrow \uparrow >

Pulsed low-field electrically detected magnetic resonance

were formed between phosphorus electron and nuclear spins, and electron paramagnetic resonance transitions between these superposition states and

Engineering of Fermi level by nin diamond junction for control of charge states of NV centers

| \uparrow \uparrow >

Electron paramagnetic resonance study of MgO thin-film grown on silicon

or

Deterministic Electrical Charge-State Initialization of Single Nitrogen-Vacancy Center in Diamond

| \downarrow \downarrow >