Project A6 - Microstructure and Structural Change of Magnetoelectric and Piezotronic Sensors

Magnetoelectric (ME) sensors for ultralow magnetic fields display complex phenomena due to their magnetic and crystallographic structure that determine their function as components of novel sensor systems with a focus on magnetic multilayer, piezotronic and surface acoustic wave (SAW) sensors. Diverse materials systems are targeted for the development of advanced analytical methods in order to elucidate these properties on multiscales and with excellent resolution and precision. A6 focuses on the complementary characterization techniques of transmission electron microscopy (TEM) and synchrotron-based X-ray scattering techniques (XRD) to meet these requirements. Using both methods, we can target our studies to investigate the structure and strain in one or in both components of ME sensors from fabrication to operation. Previously, we have focused on crystalline components. In this funding period, we intend to establish a novel methodological combination for amorphous magnetostrictive (multi)layers linking synchrotron-based pair distribution analyses with complementary electron diffraction and X-ray spectroscopy (EDX) techniques in close cooperation with the project partners from A1. Thus, in addition to crystalline information crucial for designing best quality ME sensors, atomic and magnetic structure and composition can also be interrelated for the amorphous components delivering valuable input to project A10 for a model-based structure-property description of the sensors. Moreover, the impact of heat treatment as the essential processing parameter on short-range ordering and magnetic properties will be analyzed via combined in situ XRD and TEM. Together with projects A5 and A9 crystalline piezomaterials (e.g. AlScN, GaN, ZnO) as components of novel SAW- and ΔE sensors for piezotronic readout are examined for understanding the strain behavior on multiscales and in 3D, e.g. by coherent X-ray diffraction imaging (CXDI). Particularly challenging are the envisaged combined methodological developments for new experiments of in situ electron microscopy and in operando X-ray scattering, like X-ray ptychography and atomic resolution TEM imaging techniques. These experiments require the development of novel devices for in situ straining and operando measurement in magnetic field (nano-XRD). Fewand single layer transition metal dichalcogenides (TMD) and TMD-based heterostructures (project A5 and external cooperation with D.C. Johnson from University Oregon) will be probed for their mechanoelectrical properties in situ and their application as piezotronic components of novel sensors. The ultimate goal of our research is to identify real-structure property relations and by that rules for the synthesis and design of tailor-made materials for highly sensitive and low noise ME sensors.


Involved Researchers

Person Role
Dr. Bridget Murphy
Interface Physics
Project lead
Prof. Dr. Lorenz Kienle
Materials Science
Synthesis and Real Structure
Project lead
M. Sc. Otto Lippmann
Interface Physics
PhD student
Dr.-Ing. Niklas Wolff
Materials Science
Synthesis and Real Structure
Postdoc researcher


Role within the Collaborative Research Centre

The unique combination of synchrotron based techniques and atomically resolved electron microscopy enables us to analyze the piezotronic devices (A5) as well as the multilayer materials from A1 on all relevant length scales, ex situ, in situ and operando. A6 develops new and advanced examination methods in close collaboration with these projects. Moreover, A6 establishes the competence center for advanced nanoanalytical research within the CRC. In order to identify new scientifically demanding tasks which cannot be foreseen at the present date, A6 also provides preliminary examinations for several other projects, particularly A2, A7, A9, A10 and Z1. Additional characterization of samples that is not part of the work packages will be performed by permanent staff, e.g. of the TEM center (Dr. Schürmann). Scheduled tasks are at the moment:

A1 (Magnetostrictive Multilayers for Magnetoelectric Sensors) Investigation of nanoscale structure properties of various multilayer systems.
A2 (Hybrid Magnetoelectric Sensors based on Mechanically Soft Composite Materials) Nanoscale analysis of sensor components.
A5 (Piezotronic Magnetoelectric Composites) Strain and structure in piezotronic devices.
A7 (Electrically Modulated Magnetoelectric Sensors) Structural characterization of piezoacoustic and magnetostrictive components, e.g. AlScN, FeCoSiB.
A9 (Surface Acoustic Wave Magnetic Field Sensors) Structural characterization of piezoacoustic and magnetostrictive components, e.g. AlScN, FeCoSiB.
A10 (Magnetic Noise of Magnetoelectric Sensors) Input of morphological parameters for description of suitable submodels.
Z1 (MEMS Magnetoelectric Sensor Fabrication) Advanced characterization of sensor materials to improve fabrication technology.


Project-related Publications

K. Pingen, A. M. Hinz, P. Sandström, N. Wolff, L. Kienle, L. Scipioni, J. Greer, E. von Hauff, L. Hultman, J. Birch, C.-L. Hsiao: High Growth Rate Magnetron Sputter Epitaxy of GaN Using a Solid Ga Target, Vacuum , vol. 220, 112852, 2024. 
N. Wolff, G. Schönweger, I. Streicher, Md R. Islam, N. Braun, P. Straňák, L. Kirste, M. Prescher, A. Lotnyk, H. Kohlstedt, S. Leone, L. Kienle, S. Fichtner: Demonstration and STEM Analysis of Ferroelectric Switching in MOCVD-Grown Single Crystalline Al0.85Sc0.15N, Adv. Phys. Res., 2300113, 2024. 
K. Pingen, S. Neuhaus, N. Wolff, L. Kienle, A Žukauskaitė, E. von Hauff, A. M. Hinz: Influence of Si(111) Substrate Off-Cut on AlN Film Crystallinity Grown by Magnetron Sputter Epitaxy, Journal of Applied Physics, vol. 134, issue 2, 2023. 
G. Schönweger, N. Wolff, Md R. Islam, M. Gremmel, A. Petraru, L.Kienle, H.Kohlstedt, S. Fichtner: In-Grain Ferroelectric Switching in Sub-5 nm Thin Al0.74Sc0.26N Films at 1 V, Advanced Science, 2302296, 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.
R. Guido, P. D. Lomenzo, Md R. Islam, N. Wolff, M. Gremmel, G. Schönweger, H. Kohlstedt, L. Kienle, T. Mikolajick, S. Fichtner, U. Schroeder: Thermal Stability of the Ferroelectric Properties in 100 nm-Thick Al0.72Sc0.28N, ACS Appl. Mater. Interfaces, vol. 15, issue 5, p. 7030–7043, 2023.
Md R. Islam, G. Schönweger, N. Wolff, A. Petraru, H. Kohlstedt, S. Fichtner, L. Kienle: A Comparative Study of Pt/Al0.72Sc0.28N/Pt-Based Thin-Film Metal-Ferroelectric-Metal Capacitors on GaN and Si Substrates, ACS Appl. Mater. Interfaces 15, 35, 41606–41613, 2023. 
G. Masciocchi, J. W. van der Jagt, M.-A. Syskaki, A. Lamperti, N. Wolff, A. Lotnyk, J. Langer, L. Kienle, G. Jakob, B. Borie, A. Kehlberger, D. Ravelosona, M. Kläui: Control of Magnetoelastic Coupling in Ni/Fe Multilayers using He+ ion Irradiation, Appl. Phys. Lett., vol. 121, issue 18 , 182401, 2022.
G. Schönweger, Md. R. Islam, N. Wolff, A. Petraru, L. Kienle, H.Kohlstedt, S.Fichtner: Ultrathin Al1−xScxN for Low-Voltage-Driven Ferroelectric-Based Devices, PSS rapid research letters, vol. 17, issue 1, 2200312, 2023.
N. Wolff, M. R. Islam, L. Kirste, S. Fichtner, F. Lofink, A. Žukauskaitė, L. Kienle: Al1−xScxN Thin Films at High Temperatures: Sc-Dependent Instability and Anomalous Thermal Expansion, Micromachines, no. 13, issue 8 , 01282, 2022.
M. T. Bodduluri , B.Gojdka , N.Wolff , L. Kienle , T. Lisec, F. Lofink: Article Investigation of Wafer-Level Fabricated Permanent Micromagnets for MEMS, Micromachines , no. 13, issue 5, pp. 742, 2022.
J. Su , S. Fichtner , M. Zubair Ghori , N. Wolff , M. R. Islam , A. Lotnyk , D. Kaden , F. Niekiel, L. Kienle, B. Wagner, F. Lofink: Growth of Highly c-Axis Oriented AlScN Films on Commercial Substrates, Micromachines , no. 13, issue 5, pp. 783, 2022.
G. Schönweger, A. Petraru, Md R. Islam, N. Wolff, B.t Haas, A. Hammud, C. Koch, L. Kienle, H. Kohlstedt, S. Fichtner: From Fully Strained to Relaxed: Epitaxial Ferroelectric Al1-xScxN for III-N Technology, Advanced Functional Materials, no. 32, issue 21 , pp. 2109632, 2022.
N. Wolff, T. Braniste, H.Krüger, S. Mangelsen, Md R.Islam, U. Schürmann, L. M. Saure, F. Schütt, S. Hansen, H.Terraschke, R.Adelung, I. Tiginyanu, L. Kienle: Synthesis and Nanostructure Investigation of Hybrid β-Ga2O3/ZnGa2O4 Nanocomposite Networks with Narrow-Band Green Luminescence and High Initial Electrochemical Capacity, Small, vol. 19, issue 18, 2207492, 2023.
L. Bumke, N. Wolff, C. Chluba, T. Dankwort, L. Kienle, E. Quandt: Coherent Precipitates as a Condition for Ultra-Low Fatigue in Cu-Rich Ti53.7Ni24.7Cu21.6 Shape Memory Alloys, Shape Memory and Superelasticity, volume 7, pp. 526–540, 2021.
P. Jordt, N. Wolff, S. B. Hrkac, S. Shree, D. Wang, R. J. Harder, C. Kübel, R. Adelung, O. G. Shpyrko, O. M. Magnussen, L. Kienle, B. M. Murphy: Visualizing Intrinsic 3D-Strain Distribution in Gold Coated ZnO Microstructures by Bragg Coherent X-Ray Diffraction Imaging and Transmission Electron Microscopy with Respect to Piezotronic Applications, Advanced Electronic Materials, vol. 7, issue 11, 2100546, 2021.
P. Pop-Ghe, N. Wolff, A. Rubab, L. Kienle, E. Quandt: Tailoring Growth Modes by Excess Alkali Addition in Magnetron Sputtered Potassium Sodium Niobate Thin Films, Materials Today Communications (2021), vol. 27, 102221, 2021.
P. Jordt, S. B. Hrkac, J. Gröttrup, A. Davydok, C. Krywka, N. Wolff, L. Kienle, R. Adelung, O. M. Magnussen, B. M. Murphy: Local Strain Distribution in ZnO Microstructures Visualized with Scanning Nano X-Ray Diffraction and Impact on Electrical Properties, Advanced Engineering Materials, vol. 23, issue 11, 110871, 2021.
M.R. Islam, N. Wolff, M. Yassine, G. Schönweger, B. Christian, H. Kohlstedt, O. Ambacher, F. Lofink, L. Kienle, S. Fichtner: On the Exceptional Temperature Stability of Ferroelectric Al1-xScxN Thin Films, Applied Physics Letters, vol. 118, issue 23, 232905, 2021.
N. Wolff, P. Jordt, J. Jetter, H. Vogt, A. Lotnyk, K. Seemann, S. Ulrich, E. Quandt, B. M. Murphy, L. Kienle: Nanostabilization of Tetragonal Distorted FeCo Variants in Ultra-Thin FeCo/TiN Multilayer Films, Materials Characterization, vol. 172, 110871, 2021.
N. Wolff, S. Fichtner, B. Haas, M.R. Islam, F. Niekiel, M. Kessel, O. Ambacher, C. Koch, B. Wagner, F. Lofink, L. Kienle: Atomic Scale Confirmation of Ferroelectric Polarization Inversion in Wurtzite-Type AlScN, Journal of Applied Physics, vol. 129, issue 3, 034103, 2021.
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.
L. Siebert, N. Wolff, N. Ababii, M. Terasa, O. Luopan, A. Vahl, V. Duppel, H. Qiu, M. Tienken, M. Mirabelli, V. Sontea, F. Faupel, L. Kienle, R. Adelung: Facile Fabrication of Semiconducting Oxide Nanostructures by Direct Ink Writing of Readily Available Metal Microparticles and their application as Low Power Acetone Gas Sensors, Nano Energy, vol. 70, issue 2, 104420, 2020.
X. Tao, H. Jin, M. Mintken, N. Wolff, Y. Wang, R. Tao, Y. Li, H. Torun, J. Xie, J. Luo, J. Zhou, Q. Wu, S. Dong, J. Luo, L. Kienle, R. Adelung, Y. K. Mishra, Y. Q. Fu: Three-Dimensional Tetrapodal ZnO Microstructured Network Based Flexible Surface Acoustic Wave Device for Ultraviolet and Respiration Monitoring Applications, ACS Applied Nano Materials, vol. 3, issue 2, pp. 1468–1478, 2020.
N. Wolff, V. Ciobanu, M. Enachi, M. Kamp, T. Braniste, V. Duppel, S. Shree, S. Raevschi, M. Mendina-Sánchez, R. Adelung, G. Schmidt, L. Kienle, I. Tiginyanu: Advanced Hybrid GaN/ZnO Nanoarchitectured Microtubes for Fluorescent Micromotors Driven by UV Light, small, vol. 16, issue 2, 1905141, 2019.
S. Fichtner, N. Wolff, F. Lofink, L. Kienle, B. Wagner: AlScN: A III-V Semiconductor Based Ferroelectric, Journal of Applied Physics, vol. 125, issue 11, 114103, 2019.
N. Wolff, V. Hrkac, J. Ditto, V. Duppel, Y. Mishra, D. Johnson, R. Adelung, L. Kienle: Crystallography at the Nanoscale: Planar Defects in ZnO Nanospike, Journal of Applied Crystallography, vol. 52, pp. 1009-1015, 2019.
N. Wolff, P. Jordt, T. Braniste, V. Popa, E. Monaico, V. Ursaki, A. Petraru, R. Adelung, B. Murphy, L. Kienle, I. Tiginyanu: Modulation of Electrical Conductivity and Lattice Distortions in Bulk HVPE-Grown GaN, ECS Journal of Solid State Science and Technology, vol. 8, pp. 141–146, 2019.
E. Hadland, H. Jang, N. Wolff, R. Fischer, A. Lygo, G. Mitcheson, D. Li, L. Kienle, D. Cahill, D. Johnson: Ultralow Thermal Conductivity of Turbostratically Disordered MoSe2 Ultra-Thin Films and Implications for Heterostructures, Nanotechnology, vol. 30, no. 28, 285401, 2019.
O. Lupan, V. Postica, N. Wolff, J. Su, F. Labat, I. Ciofini, H. Cavers, R. Adelung, O. Polonskyi, F. Faupel, L. Kienle, B. Viana, T. Pauporté: Low-Temperature Solution Synthesis of Au-Modified ZnO Nanowires for Highly Efficient Hydrogen Nanosensors, ACS Applied Materials and Interfaces, vol. 11, issue 35, pp. 32115-32126, 2019.
V. Postica, I. Paulowicz, O. Lupan, F. Schütt, N. Wolff, A. Cojocaru, YK. Mishra, L. Kienle, R. Adelung: The Effect of Morphology and Functionalization on UV Detection Properties of ZnO Networked Tetrapods and Single Nanowires, Vacuum, vol. 166, pp. 393-398, 2019.
A. Piorra, V. Hrkac, N. Wolff, C. Zamponi, V. Duppel, J. Hadermann, L. Kienle, E. Quandt: (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 Thin Films Prepared by PLD: Relaxor Properties and Complex Microstructure, Journal of Applied Physics, vol. 125, issue 24, 244103, 2019.
I. Paulowicz, V. Postica, O. Lupan, N. Wolff, S. Shree, A. Cojocaru, M. Deng, Y. K. Mishra, I. Tiginyanu, L. Kienle, R. Adelung: Zinc Oxide Nanotetrapods with Four Different Arm Morphologies for Versatile Nanosensors, Sensors and Actuators B: Chemical, vol. 262, pp. 425-435, 2018.
O. Lupan, N. Wolff, V. Postica, T. Braniste, I. Paulowicz, V. Hrkac, Y. K. Mishra, I. Tiginyanu, L. Kienle, R. Adelung: Properties of a Single SnO2:Zn2SnO4 - Functionalized Nanowire Based Nanosensor, Ceramics International, vol. 44, issue 5, pp. 4859-4867, 2018.
M. Hoppe, O. Lupan, V. Postica, N. Wolff, V. Duppel, L. Kienle, I. Tiginyanu, R. Adelung: ZnAl2O4-Functionalized Zinc Oxide Microstructures for Highly Selective Hydrogen Gas Sensing Applications, Physica Status Solidi A, vol. 215, issue 7, 2018.
U. Schürmann, C. Chluba, N. Wolff, D. Smazna, R. Lima de Miranda, P. Junker, R. Adelung, E. Quandt, L. Kienle: Functional NiTi Grids for in situ Straining in the TEM, Ultramicroscopy, vol. 182, pp. 10-16, 2017. 
S. B. Hrkac, C. T. Koops, M. Abes, C. Krywka, M. Müller, M. Burghammer, M. Sztucki, T. Dane, S. Kaps, Y. K. Mishra, R. Adelung, J. Schmalz, M. Gerken, E. Lage, C. Kirchhof, E. Quandt, O. M. Magnussen, B. M. Murphy: Tunable Strain in Magnetoelectric ZnO Microrod Composite Interfaces, ACS Appl. Mater. Interfaces, 9 (30), pp. 25571–25577 , 2017.
D. Smazna, N. Wolff, S. Shree, F. Schütt, Y.K. Mishra, L. Kienle, R. Adelung: Enhancing the Conductivity of ZnO Micro- and Nanowire Networks with Gallium Oxide, IEEE 7th International Conference Nanomaterials: Application and Properties (NAP), Odessa, pp. 01FNC07-1-01FNC07-5, 2021.
S. Fichtner, N. Wolff, G. Krishnamurthy, A. Petraru, S. Bohse, F. Lofink, S. Chemnitz, H. Kohlstedt, L. Kienle, B. Wagner: Identifying and Overcoming the Interface Originating C-Axis Instability in Highly Sc Enhanced AlN for Piezoelectric Micro-Electromechanical Systems, Journal of Applied Physics, vol. 122, issue 3, 035301, 2017.
S. Kaps, S. Bhowmick, J. Gröttrup, V. Hrkac, D. Stauffer, H. Guo, O. L. Warren, J. Adam, L. Kienle, A. M. Minor, R. Adelung, Y. K. Mishra: Piezoresistive Response of Quasi-One-Dimensional ZnO Nanowires Using an in Situ Electromechanical Device, Acs Omega, 2(6), pp. 2985-2993, 2017.
E. Yarar, V. Hrkac, C. Zamponi, A. Piorra, L. Kienle, E. Quandt: Low Temperature Aluminum Nitride Thin Films for Sensory Applications, AIP Advances, 6 , 075115, 2016.
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.