Project A1 - Magnetostrictive Multilayers for Magnetoelectric Sensors

Project A1 focuses on individual magnetostrictive layer conceptual design, deposition, and post-processing, assisted by in-depth volumetric magnetic characterization, and lateral and time-resolved magnetic imaging. The overall aim of the project is to implement new layer systems with higher signal sensitivity while eliminating magnetic noise sources that degrade the performance of magnetoelectric (ME) sensors. One objective is to further improve the detection limit of ME sensors while at the same time limiting magnetic domain activity with advanced magnetic layer designs. A second key objective is to introduce specific layer systems for the various sensor concepts that will allow the sensors to operate without external magnetic bias fields and to provide directional sensor response for vector field measurements.

The approach based on magnetron sputter deposition allows the deposition of complex magnetic multilayer structures with a high degree of design freedom. Post film deposition magnetic anisotropy tailoring enables additional sensitivity and working point adjustments. Magnetic coupling effects across interfaces and structural edges are used to resolve the antagonism of achieving high sensitivity and low magnetic noise, while taking into account the different sensor-specific requirements arising from the respective sensor dimensions, excitation schemes, and application scenarios. We have shown that magnetic or electrical excitation of modulated sensors lead to magnetic domain activity, thereby increasing the level of magnetic noise. As a solution to improved limit of detection, different individual soft magnetic film concepts have been established for ΔE (A4), converse ME (A7) and SAW sensors (A9), which stay single domain. In the proposed funding period, the portfolio of layer concepts will be further extended to solutions for exhibited noise generating nonlinear sensor characteristics, low losses at high operation frequencies, and higher temperature resistance in line with new or modified sensor concepts in projects A4, A7, A9, and Z1. Magnetic property adjustable layer structures that can be precisely tuned to the required sensor characteristics, in particular with working point and bias tunability will be investigated. For the envisioned applications (see B9, B10, B12, B13), zero-field detectivity and defined directional sensor response will be realized by magnetic layer design. Material properties and magnetic noise issues will be investigated together with project A6, respectively, with projects B1 and A10.

Involved Researchers

Person		Role
	Prof. Dr. Jeffrey McCord Materials Science Nanoscale Magnetic Materials	Project lead
	Dr. Dirk Meyners Materials Science Inorganic Functional Materials	Project lead
	M.Sc. Dennis Seidler Materials Science Nanoscale Magnetic Materials	Doctoral researcher
	M.Sc. Lars Thormählen Materials Science Inorganic Functional Materials	Doctoral researcher

Role within the Collaborative Research Centre

A1 plays a central role within the CRC to achieve a designed ME response with high detectability. We will collaborate on the sensor fabrication and magnetic characterization with the groups in research area A, particularly with A4, A7 and A9. A cooperation on integration issues will be conducted with Z1. A1 will contribute to the focus groups F1 - Magnetic Layers to F5 - Concepts based on Delta-E Effect. Collaborations with the following projects are foreseen:

Project-related Publications

F. Block, F. Klingbeil, U. Sajjad, C. Arndt, S. Sindt, D. Seidler, L. Thormählen, C. Selhuber-Unkel, J. McCord: Magnetic Bucket Brigade Transport Networks for Cell Transport, Advanced Materials Technologies, pp. 2300260, 2023.

V. Schell, E. Spetzler, N. Wolff, L.Bumke, L. Kienle, J. McCord, E. Quandt, D. Meyners: Exchange Biased Surface Acoustic Wave Magnetic Field Sensors, Scientific Reports, vol. 13, no. 8446, 2023.

A. Kumar, E. Lyzhko, L. Hamid, A. Srivastav, U. Stephani, N. Japaridze:  Neuronal Networks Underlying Ictal and Subclinical Discharges in Childhood Absence Epilepsy, J Neurol, Mar., 270(3), 1402-1415, 2023.

E. Elzenheimer, P. Hayes, L. Thormählen, E. Engelhardt, A. Zaman, E. Quandt, N. Frey, M. Höft, G. Schmidt: Investigation of Converse Magnetoelectric Thin Film Sensors for Magnetocardiography, IEEE Sensors Journal Print ISSN, pp. 5660-5669, 2023.

F. Schlichting, L. Thormählen, J. Cipo, D. Meyners, H. Kersten: Energy-dependent Film Growth Of Cu And NiTi From A Tilted DC Magnetron Sputtering Source Determined By Calorimetric Probe Analysis, Surface and Coatings Technology, 450, 129000, 2022.

J. Arbustini, J. Muñoz, H. Wang, E. Elzenheimer, J. Hoffmann, L. Thormählen, P. Hayes, F. Niekiel, H. Heidari, M. Höft, E. Quandt, G. Schmidt, A. Bahr: MEMS Magnetic Field Source for Frequency Conversion Approaches for ME Sensors, BMT2022 , Joint Annual Conference of the Austrian, German and Swiss Societies for Biomedical Engineering, 2022.

S. Moench, J. M. Meyer, A. Žukauskaitė, V. Lebedev, S. Fichtner, J. Su, F. Niekiel, T. Giese, L. Thormählen, E. Quandt, F. Lofink: AlScN-Based SAW Magnetic Field Sensor for Isolated Closed-Loop Hysteretic Current Control of Switched-Mode Power Converters, IEEE Sensors Letters, vol. 6, no. 10, pp. 1-4, 2022.

R. Schäfer, J. McCord:  Magneto-Optical Microscopy, in Magnetic measurement techniques for materials characterization, 171-229, Springer, 2023.

C. Müller, P. Durdaut, R. B. Holländer, A. Kittmann, V. Schell, D. Meyners, M. Höft, E. Quandt, J. McCord: Imaging of Love Waves and Their Interaction with Magnetic Domain Walls in Magnetoelectric Magnetic Field Sensors, Advanced Electronic Materials, 2200033, 2022.

J. M. Meyer, V. Schell, J. Su, S. Fichtner, E. Yarar, F. Niekiel, T. Giese, A. Kittmann, L. Thormählen, V. Lebedev, S. Moench, A. Žukauskaitė, E. Quandt, F. Lofink: Thin-Film-Based SAW Magnetic Field Sensors, Sensors, vol. 21, no. 24, 8166, 2021.

L. Thormählen, D. Seidler, V. Schell, F. Munnik, J. McCord, D. Meyners: Sputter Deposited Magnetostrictive Layers for SAW Magnetic Field Sensors, Sensors, vol. 21, issue 24, 8386, 2021.

F. Block, F. Klingbeil, S. Deshpande, U. Sajjad, D. Seidler, C. Arndt, S. Sindt, C. Selhuber-Unkel, J. McCord: Unidirectional Transport of Superparamagnetic Beads and Biological Cells Along Oval Magnetic Elements, Applied Physics Letters, vol. 118, issue 23, 232405, 2021.

B. Spetzler, E. V. Golubeva, R.-M. Friedrich, S. Zabel, C. Kirchhof, D. Meyners, J. McCord, F. Faupel: Magnetoelastic Coupling and Delta-E Effect in Magnetoelectric Torsion Mode Resonators, Sensors, vol. 21, no. 6, 2021.

J. Su, F. Niekiel, S. Fichtner, L. Thormaehlen, C. Kirchhof, D. Meyners, E. Quandt, B. Wagner, F. Lofink: AlScN-Based MEMS Magnetoelectric Sensor, Applied Physics Letters, vol. 117, issue 13, 132903, 2020.

S. M. Curtis, N. Wolff, D. Dengiz, H. Lewitz, J. Jetter, L. Bumke, P. Hayes, E. Yarar, L. Thormählen, L. Kienle, D. Meyners, E. Quandt: Integration of AlN Piezoelectric Thin Films on Ultralow Fatigue TiNiCu Shape Memory Alloys, Journal of Materials Research 35, no. 10, pp. 1298–1306, 2020.

S. Salzer, V. Röbisch, M. Klug, P. Durdaut, J. McCord, D. Meyners, J. Reermann, M. Höft, R. Knöchel: Noise Limits in Thin-Film Magnetoelectric Sensors With Magnetic Frequency Conversion, IEEE Sensors Journal, vol. 18, no. 2, pp. 596-604, 2018.

A. Kittmann, P. Durdaut, S. Zabel, J. Reermann, J. Schmalz, B. Spetzler, D. Meyners, N. X. Sun, J. McCord, M. Gerken, G. Schmidt, M. Höft, R. Knöchel, F. Faupel, E. Quandt: Wide Band Low Noise Love Wave Magnetic Field Sensor System, Scientific Reports, vol. 8, no. 278, 2018.

P. Durdaut, S. Salzer, J. Reermann, V. Röbisch, J. McCord, D. Meyners, E. Quandt, G. Schmidt, R. Knöchel, M. Höft: Improved Magnetic Frequency Conversion Approach for Magnetoelectric Sensors, IEEE Sensors Letters, vol. 1, no. 3 , 2017.

P. Durdaut, S. Salzer, J. Reermann, V. Röbisch, P. Hayes, A. Piorra, D. Meyners, E. Quandt, G. Schmidt, R. Knöchel, M. Höft: Thermal-Mechanical Noise in Resonant Thin-Film Magnetoelectric Sensors, IEEE Sensors Journal, vol. 17, no. 8, pp. 2338-2348, 2017.

S. Salzer, P. Durdaut, V. Röbisch, D. Meyners, E. Quandt, M. Höft, R. Knöche: Generalised Magnetic Frequency Conversion for Thin Film Laminate Magnetoelectric Sensors, EEE Sensors Journal, vol. 17, no. 5, pp. 1373-1383, 2017.

V. Röbisch, S. Salzer, N. O. Urs, J. Reermann, J. Yarar, A. Piorra, C. Kirchhof, E. Lage, M. Höft, G. Schmidt, R. Knöchel, J. McCord, E. Quandt, M. Meyners: Pushing the Detection Limit of Thin Film Magnetoelectric Heterostructures, Journal of Materials Research, vol. 32, issue 6, pp. 1009-1019, 2017.

M. Abes, C. T. Koops, S. B. Hrkac, J. McCord, N. O. Urs, N. Wolff, L. Kienle, W. J. Ren, L. Bouchenoire, B. M. Murphy, O. M. Magnussen: Domain Structure and Reorientation in CoFe2O4, Physical Review B 93 , 195427, 2016.