Chiral nanospintronics

V.V. Ustinov, L.I. Naumova, M.A. Milyaev, R.S. Zavornitsyn, I.A. Yasyulevich

A quantum theory of electron spin transport in conducting magnetics has been constructed, describing a whole range of new galvanomagnetic phenomena due to the action on the spin of conduction electrons of forces created by spatially inhomogeneous external magnetic fields and/or internal fields of quantum exchange origin. The existence of two new spin-transport effects in conducting chiral helimagnetics, which were named "electric magnetochiral Stern-Gerlach effect" and "kinetic magnetoelectric Stern-Gerlach effect", is predicted and fully described. The conditions for experimental observation of the phenomenon of resonant amplification of new effects up to giant magnitudes, named "magnetochiral kinetic resonance", have been determined. New magnetic nanoheterostructures of the "chiral spin valve" type based on Ho and Dy helimagnetics have been synthesized, and the possibility of effective control of their magnetotransport characteristics by rotation of a magnetic helix of finite size in the chiral layer having an uncompensated magnetic moment under the action of an external magnetic field has been shown experimentally.

 

Spin valve with dysprosium layer as a tool for studying helicoidal magnetism

V.V. Ustinov, M.A. Milyaev, L.I. Naumova, R.S. Zavornitsyn, T.P. Krinitsina, V.V. Proglyado

A new method for studying the magnetic state of helimagnetic films based on the use of a spin valve containing a helimagnetic layer as a magnetosensitive "device" is proposed. It is shown that the shape of the field dependence of the magnetoresistance of the Ta/NiFe/CoFe/Cu/CoFe/Dy/CoFe/FeMn/Ta spin valve changes at the transition of the dysprosium layer into a state with helicoidal ordering. The analysis of magnetoresistive data allowed us to obtain information on the temperature change of the angle between the magnetic moments of the CoFe layers exchange-bonded with the magnetic moments of the dysprosium layer in the CoFe/Dy interfaces.

 

Co90Fe10/Cu superlattices with record magnetoresistance

M.A. Milyaev, L.I. Naumova, N.S. Bannikova, T.P. Krinitsina, V.V. Proglyado, T.A. Chernyshova, V.V. Proglyado, T.A. Chernyshova, V.V. Ustinov

Magnetic superlattices Co90Fe10/Cu with magnetoresistance values of 83% at room temperature and over 165% at helium temperatures have been synthesized for the first time. These values are record values for superlattices of this composition and exceed the corresponding magnetoresistance values obtained earlier in the laboratory of IBM (S. Parkin) and in other scientific centres. These results were obtained using a special composite buffer layer Ta/Ni48Fe12Cr40, which promotes the formation of a perfect crystalline structure in the layers of the superlattice, during the multi-step optimization of the composition of the multilayer structure and the development of technological modes of obtaining nanostructures by magnetron sputtering.