Rare-earth-free Ferrimagnetic Mn4N Spintronics

Preface

Acknowledgements

Author biography

List of symbols

1 Introduction

1.1 Origin of magnetic moment

1.1.1 Orbital magnetic moment

1.1.2 Spin magnetic moment

1.1.3 Spin-orbit interaction

1.2 Magnetic properties of ferrimagnet

1.2.1 Classification of magnetic materials

1.2.2 Magnetization process of materials

1.2.3 Energies in ferromagnets

1.2.4 Magnetic domain and magnetic domain wall

1.3 Magnetic domain wall dynamics

1.3.1 LLG equation

1.3.2 Spin-transfer torque (STT)

1.3.3 Spin-orbit torque (SOT)

1.4 Spintronics applications of ferrimagnet

1.4.1 Devises using domain wall motion

1.4.2 DW motion in ferrimagnets

1.5 Theory of current-induced DW motion

1.5.1 Current induced DW motion

1.5.2 Spin-transfer torque in ferrimagnets

1.6 Features of Mn4N

Bibliography

2 Research history of Mn4N-based mixed crystals: several research topics

2.1 Non-collinear antiferromagnetic structure of Mn3AN and Kagome lattice

2.1.1 Observation of magnetic order by neutron powder diffraction(NPD), electron spin resonance (ESR), and nuclear magnetic resonance (NMR) methods

2.1.2 Temperature dependence of magnetic properties and magnetic phase

2.2 Negative thermal expansion (NTE) and magnetovolume effects (MVE)

2.2.1 Origin of NTE phenomena in Mn3AN

2.2.2 Mochizuki-Kobayashi model: explanation for NTE phenomena

2.2.3 Relationship between magnetic order and crystal fieldin face-centered Mn

2.2.4 Relationship between nearest exchange coupling J1 and bond length ¿

2.3 Measurement of thermal coefficient of resistivity (TCR) and magnetic order

2.3.1 L-TCR materials: Mn3NiN, Mn3CuN, Mn3AgN

2.3.2 Electric properties: metal-semiconductor transition in Mn4-xAgxN and Mn4-xPdxN

Bibliography

3 Crystal and magnetic structure of Mn4N

3.1 Crystal structure of antiperovskite transition metal nitrides

3.2 Mn4N bulk crystals

3.2.1 Magnetic order by neutron diffraction

3.2.2 Magnetic compensation of impurity-doped Mn4N bulk

3.3 Mn4N thin films 3-4 3.3.1 History of thin-film growth

3.3.2 Characterizations of Mn4N epitaxial films on MgO(001) and SrTiO3(001)

3.3.3 Correlation between lattice distortion and perpendicular magnetic anisotropy

3.3.4 Spin-resolved density of states of Mn4N

3.3.5 X-ray magnetic circular dichroism (XMCD) measurement on Mn4N films

3.4 Summary 3-30 Bibliography

4 Ultrafast CIDWM in Mn4N strips

4.1 Fabrication process of Hall bars

4.2 Equivalency between current and magnetic field

4.3 Spin-transfer torque using direct current (DC)

4.3.1 Pinning of the DW on the notch

4.3.2 CIDWM using DC without external field assistance

4.4 Spin-transfer torque using pulsed current

4.4.1 Device fabrication

4.4.2 Speed of DWs driven by current pulses

4.4.3 Field driven DW motion

4.4.4 Origin of the high DW mobility in Mn4N

4.4.5 Estimation of the spin polarization

4.4.6 Influence of the non-adiabatic torque and the damping parameter on CIDWM

4.4.7 Damping and non-adiabatic torque: the particular case at a = ß

4.5 Summary 4-19 Bibliography

5 Growth and characterization of compensated Mn4N epitaxial films

5.1 Mn4-xZxN (Z=Ge, Ga, Zn, Cu, Ni, Sn, In, Cd, Ag, Pd) powders

5.2 Mn4-xNixN epitaxial films 5-3 5.2.1 Growth of Mn4-xNixN films on SrTiO3(001) by MBE

5.2.2 Characterization of Mn4-xNixN films 5-4 5.3 Mn4-xCoxN epitaxial films

5.3.1 MBE growth of Mn4-xCoxN films on SrTiO3(001) by MBE

5.3.2 Characterization of Mn4-xCoxN films

5.4 Summary 5-16 Bibliography

6 Growth and characterization of nonmagnetic element doped Mn4N epitaxial films

6.1 Mn4-xCrxN epitaxial films

6.1.1 MBE growth of Mn4-xCrxN films on SrTiO3(001) by MBE

6.1.2 Characterization of Mn4-xCrxN films

6.2 Mn4-xInxN epitaxial films

6.2.1 MBE growth of Mn4-xInxN films on SrTiO3(001) by MBE

6.2.2 Characterization of Mn4-xInxN films

6.3 Mn4-xAuxN epitaxial films

6.3.1 MBE growth of Mn4-xAuxN films on SrTiO3(001) by MBE

6.3.2 Characterization of Mn4-xAuxN films

6.4 Mn4-xSnxN epitaxial films

6.4.1 MBE growth of Mn4-xSnxN films on SrTiO3(001) by MBE

6.4.2 Characterization of Mn4-xSnxN films

6.5 Summary

Bibliography

7 Ultrafast CIDWM in compensated Mn4N strips

7.1 Reaching the compensation point

7.2 Growth and structural characterization

7.3 Magnetization and transport measurements

7.4 Current induced domain wall motion

7.5 Analytical modeling of the two sub-lattice system

7.6 First-principles calculations and analysis

7.7 Analytical modeling of Joule heating in Mn4N wires

7.8 Summary

Bibliography

8 Properties of Mn4N-based mixed crystals sorted by doped element

8.1 Mn4-xAlxNy

8.1.1 Magnetic, electrical, and thermoelectric properties in Mn3AlNy (y = 1.0, 1.1, 1.2)

8.1.2 First-principles calculation of magnetic properties and electronic structure

8.2 Mn4-xCrxNy

8.3 Mn4-xFexN

8.3.1 Magnetic properties of bulk samples

8.3.2 Change from in-plane magnetic anisotropy for Fe4N to perpendicular magnetic anisotropy for Mn4N in Mn4-xFexN thin films on MgO(001)

8.3.3 First-principles calculation for Mn4-xFexN

8.4 Mn4-xCoxN 8-7 8.4.1 Crystalline quality of thin films and magnetic and magneto-transport properties

8.4.2 Discovery of exchange bias and observation of magnetic order in Mn3.39Ni0.61N by NPD

8.5 Mn4-xNixN

8.5.1 Piezomagnetic effect (PME) and Barocaloric effect (BCE) in Mn3NiN

8.5.2 First-principles calculation of spin-phonon coupling in Mn3NiN

8.6 Mn4-xCuxN

8.6.1 Magnetostriction and ferromagnetic shape memory effect (FSME) in Mn3CuN

8.6.2 Magneto-transport properties in Mn3CuN thin films

8.7 Mn4-xZnxN

8.8 Mn4-xGaxN

8.9 Mn4-xGexN

8.10 Mn4-xRhxN

8.11 Mn4-xPdxN

8.12 Mn4-xAgxN

8.13 Mn4-xInxN

8.14 Mn4-xSnxN

8.15 Mn4-xSbxN

8.16 Mn4-xPtxN

8.17 Mn4-xAuxN

8.18 Mn4-xGdxN

8.19 Mn4-xDyxN

Bibliography

9 Recent progress

9.1 Ultrathin film growth

9.2 Magnetic skyrmions and Dzyaloshinskii Moriya interaction

9.2.1 Observation of magnetic skyrmions

9.2.2 DMI measurement

9.3 SOT switching

9.4 Anomalous Nernst effect

9.5 Modulation of the magnetic properties by light element doping

9.6 Perspective

Bibliography