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Yelyzaveta Mala - European Fusion Teacher Day 2025

10/10/2025

Agenda

My path from plasma to spintronics (from studies in Ukraine to PhD in Germany)
Plasma-Spin-Energy German-Ukrainian Core of Excellence
Plasma in science
Thin film deposition
Spintronics
Characterizations
Sputtering effect on thin films in spintronic
Devices & industry

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Yelyzaveta Mala - European Fusion Teacher Day 2025

10/10/2025

Educational Background

2006 - 2017 Secondary school №62, Kharkiv, Ukraine

V.N. Karazin Kharkiv National University:

2017 - 2021 Bachelor`s degree - applied physics and nanomaterials

2021 - 2022 Master’s degree - applied physics and nanomaterials

National Science Center KIPT, Institute of Plasma Physics

2021 - 2022 Experimental part for the Bachelor thesis:

“Optical emission spectroscopy methods for analysis of high-energy plasma streams density.”

Max Planck Institute of Microstructure Physics:

2022 3 months internship and experimental part for the Master thesis:

“Formation of spintronic structures by magnetron sputtering.”

2023 – 2025 Research assistant in Samsung project

2025 – present PhD student at the NISE department of the Max Planck Institute as part of the German-

Ukrainian Core of Excellence “Plasma-Spin-Energy”

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Yelyzaveta Mala - European Fusion Teacher Day 2025

10/10/2025

Plasma-Spin-Energy

German-Ukrainian Core of Excellence

The main goal:

bring together novel spintronics and plasma technologies;
involving Ukrainian scientists from all over the world;
perform groundbreaking research.

Scientific partners:

Max Planck Institute of Microstructure Physics (MPI);
V.N. Karazin Kharkiv National University;
National Science Center Kharkiv Institute of Physics and Technology (NSC KIPT).

CoE one of the four best project concepts in Ukraine that were selected for funding from Federal Ministry of Education and Research (BMBF) with 2.5 million euros.

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Yelyzaveta Mala - European Fusion Teacher Day 2025

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Plasma-Spin-Energy

German-Ukrainian Core of Excellence

New equipment for the CoE team at Karazin University

Research visits of Ukrainian colleagues to MPI-MSP

CoE team at the “Frontiers of Racetrack Memory” workshop

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Yelyzaveta Mala - European Fusion Teacher Day 2025

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Plasma in science & technology

Applications:

Physics & Research: fusion, astrophysics, plasma diagnostics;
Industry: microelectronics, coating, thin film deposition
Medicine: sterilization, wound heating, cancer treatment
Everyday life: plasma TVs, fluorescent lamps, plasma cutting

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Yelyzaveta Mala - European Fusion Teacher Day 2025

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Deposition techniques

Technique	Schematic	Principle	Typical Use
CVD (Chemical Vapor Deposition)/ PECVD		Gas precursors -> reach heated substrate / plasma activates molecules -> react chemically -> film	Semiconductors, coatings
ALD (Atomic Layer Deposition)		Gas A injected -> reacts with surface -> one atomic layer -> purged -> Gas B injected -> second reaction (cycle repeats)	Ultra-thin coating
PVD (Physical Vapor Deposition)		Solid source -> heated or vaporized -> atoms travel -> condense on substrate -> film forms physically	Metals, oxides
Sputtering (type of PVD)		Energetic ions from plasma -> bombard a target -> atoms ejected -> fly through gas -> deposit on substrate as thin film	Magnetic films, electronics, spintronics

DOI:10.3866/PKU.WHXB201804201

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Yelyzaveta Mala - European Fusion Teacher Day 2025

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Magnetron sputtering

Sputtering (type of PVD)		Energetic ions from plasma -> bombard a target -> atoms ejected -> fly through gas -> deposit on substrate as thin film	Magnetic films, electronics, spintronics

Advantages of magnetron sputtering:

Clean & contamination-free;
Excellent thickness & composition control;
Suitable for many materials (metals, oxides, multilayers);
Widely used in science and industry.

The magnetron enhances sputtering by using a magnetic field to confine electrons near the target, increasing ionization and sputter rate.

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Yelyzaveta Mala - European Fusion Teacher Day 2025

10/10/2025

Category	Type
Power source	DC
	RF
Gas environment	Inert (Ar, Xe, Kr)

Target	Single
	Multiple / Co-sputtering

Deposition system - MANGO

3 ion sources
12 targets
12 magnetron source
4 clusters
36 different materials

General view of the MANGO installation

MPI of Microstructure Physics

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Yelyzaveta Mala - European Fusion Teacher Day 2025

10/10/2025

Why thin films matter?

Thin films are used in many modern technologies:

electronics, optics, coating, sensors, and energy systems.

Enable precise control of material properties at the nanoscale.
In spintronics, thin magnetic layers are essential for memory devices that controls by spin transport.
Magnetron sputtering provides the precision and quality needed to grow these complex multilayer systems for next-generation, energy-efficient memory and sensor devices.

esssolarpower

10.1038/s41598-019-48311-0

hardinoptical

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Yelyzaveta Mala - European Fusion Teacher Day 2025

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Spintronics

Spintronics (spin + electronics) is a field of condensed matter physics that uses both the charge and the spin of electrons to store and process information.

Every electrons has a spin (intrinsic form of angular momentum) that can be up ↑ or down ↓ and create spin-polarized current in magnetic thin films.

Spin up ↑

Spin down ↓

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Yelyzaveta Mala - European Fusion Teacher Day 2025

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Spintronic mechanisms and effects

Spintronic devices rely on multiple physical mechanisms like:

Spin Hall effect (SHE): charge current -> spin current;
Rashba effect: interface, spin splitting;
Spin transfer torque (STT): spin current exerts torque -> M switching;
Spin orbit torque (SOT): heavy metal -> spin current -> M switching;
Tunnel magnetoresistance: electrons tunnel through insulator;
Exchange coupling: magnetic layers -> spins align parallel or antiparallel through spacer.

All of them strongly depends on the materials choice, layer thickness, and deposition parameters.

R. Bläsing et al., Proceedings of the IEEE, 108, 1308 (2020)

FM TB FM

Spin Hall effect

Rashba effect

SOT in domain wall (DW) motion

Tunneling

Interlayer exchange coupling

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Yelyzaveta Mala - European Fusion Teacher Day 2025

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How we characterize thin films?

To understand how growth conditions affects film properties
To verify structure, composition, and interfaces

Structural / Morphological	Magnetic	Electrical / Transport	Chemical / Compositional
XRD -> crystal structure, texture	VSM -> hysteresis loops, magnetic moment	CIPT -> magnetoresistance (GMR/TMR)	XPS -> surface chemistry, oxidation states
XRR -> layer thickness, density, roughness	MOKE -> switching, Kerr rotation	4-probe -> sheet resistance, conductivity	RBS -> elemental composition, depth profiling
AFM -> surface morphology, roughness	Kerr microscope -> magnetic domains	PPMS -> magnetoresistance, Hall effect, temperature dependence	EDS / EDX -> elemental mapping in SEM/TEM
SEM -> surface structure, grain size	SQUID -> sensitive magnetic moment (low signal)	CIP / CPP -> spin transport	SIMS -> depth profiling, impurities
TEM / HRTEM -> crystal lattice, interfaces	FMR -> magnetic damping, resonance		Auger / AES -> surface composition (nm scale)

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Structural / morphological characterization

Reveals crystal structure, phase, and texture;

Determine thickness, roughness, and grain size;

Key methods: XRD (XRR), AFM, SEM, TEM / HRTEM;

Important for verifying multilayer quality and interfaces.

XRD equipment

XRR measurement

XRD spectra

AFM measurement

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Yelyzaveta Mala - European Fusion Teacher Day 2025

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Determines elemental composition, oxidation states and purity;

Confirms stoichiometry in compound films (oxides, or interdiffusion);

Tools: EDS, XPS, SIMS, RBS;

Crucial understanding spintronics stacks.

10.1021/acsomega.3c02457

Chemical / composition characterization

Schematic of XPS setup

XPS measurements

EDS measurement

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Magnetic characterization

Measures magnetization, coercivity, anisotropy, domains…;

Tools: VSM, MOKE, Kerr Microscope, SQUID;

Reveals magnetic domain structure and switching behavior;

Directly linked to spintronic device performance.

↑↓ domain wall

VSM equipment

Kerr microscope measurements

VSM measurement

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Yelyzaveta Mala - European Fusion Teacher Day 2025

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Electrical characterization

Evaluates resistivity, magnetoresistance, and tunneling properties;

Techniques: CIPT, 4-point probe, PPMS, CIP/CPP;

Determines device efficiency (↑TMR)

Helps correlate structures and magnetism with spin transport

Bruker

Schematic diagram of CIPT

CIPT measurement

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Yelyzaveta Mala - European Fusion Teacher Day 2025

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Deposition parameters overview

Parameters	Mechanism
Power (DC/RF)	Controls deposition rate and energy of atoms -> density and structure
Pressure	Affects mean free path -> influences roughness, grain size, and stress
Gas composition	Determines film composition (metallic / oxide / nitride)
Substrate temperature	Controls crystallinity, diffusion, and interface quality
In-situ annealing	Control heating after or during deposition for reduce defects, enhanced crystallinity, modify anisotropy and coupling
Target-substrate dist.	Influences uniformity and deposition rate
Deposition time & rate	Determines thickness of the film

Film structure, interface quality, and all film properties are governed by deposition parameters

Control via power, pressure, gas composition, temperature, etc.

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Yelyzaveta Mala - European Fusion Teacher Day 2025

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Deposition power (DC/RF)

Direct current (DC) for metals, radiofrequency (RF) for oxides and nitrides;
Higher power -> higher plasma density and plasma flux;
Affects film growth rate, crystallinity, density, morphology.

Anas A. Ahmed et al., AIP Conf. Proc. 2068, 020076 (2019)

S. Elmassi, et al., Physica B: Condensed Matter, 659, (2023) 414853

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Pressure

Defines mean free path of ions and sputtered atoms;
Low pressure -> high energy, fewer collisions ->

dense films (but can damage previous layer);

High pressure -> more scattering -> porous structure;
Influences plasma stability and deposition rate.

3 mTorr

12 mTorr

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Gas composition

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Yelyzaveta Mala - European Fusion Teacher Day 2025

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Temperature

In-situ annealing / post annealing

Higher temperature -> improve crystallinity, magnetic coupling or start interdiffusion;
Affects adhesion, anisotropy, and interface quality (Interfaces are important!);
Promotes atomic rearrangement and defect reduction.

O1s

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Yelyzaveta Mala - European Fusion Teacher Day 2025

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Devices & industrial relevance

When the film has a good quality -> make devices -> cleanroom (lithography,…)

These spintronic devices commonly used in IBM, SAMSUNG, Intel, …

Dieny, B., et al. Nat Electron 3, 446–459 (2020).

STUART S. P. PARKIN, ET AL., Science 320, 5873 pp. 190-194 (2008)

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