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Aguirre FL, Piros E, Kaiser N, Vogel T, Petzold S, Gehrunger J, Hochberger C, Oster T, Hofmann K, Suñé J, Miranda E, Alff L. Revealing the quantum nature of the voltage-induced conductance changes in oxygen engineered yttrium oxide-based RRAM devices. Sci Rep 2024; 14:1122. [PMID: 38212346 PMCID: PMC10784569 DOI: 10.1038/s41598-023-49924-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 12/13/2023] [Indexed: 01/13/2024] Open
Abstract
In this work, the quasi-analog to discrete transition occurring in the current-voltage characteristic of oxygen engineered yttrium oxide-based resistive random-access memory (RRAM) devices is investigated in detail. In particular, the focus of our research is not on the absolute conductance values of this characteristic but on the magnitude of its conductance changes occurring during the reset process of the device. It is found that the detected changes correspond to conductance values predominantly of the order of the quantum unit of conductance G0 = 2e2/h, where e is the electron charge and h the Planck constant. This feature is observed even at conductance levels far above G0, i.e. where electron transport is seemingly diffusive. It is also observed that such behavior is reproducible across devices comprising yttrium oxide layers with different oxygen concentrations and measured under different voltage sweep rates. While the oxygen deficiency affects the total number of quantized conductance states, the magnitude of the changes in conductance, close to 1 G0, is invariant to the oxygen content of the functional layer.
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Affiliation(s)
- F L Aguirre
- Departament d'Enginyeria Electrònica, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Valles, Spain.
- Intrinsic Semiconductor Technologies, Ltd., Buckinghamshire, United Kingdom.
| | - E Piros
- Advanced Thin Film Technology Division, Institute of Materials Science, Technische Universität Darmstadt, Darmstadt, Germany.
| | - N Kaiser
- Advanced Thin Film Technology Division, Institute of Materials Science, Technische Universität Darmstadt, Darmstadt, Germany
| | - T Vogel
- Advanced Thin Film Technology Division, Institute of Materials Science, Technische Universität Darmstadt, Darmstadt, Germany
| | - S Petzold
- Advanced Thin Film Technology Division, Institute of Materials Science, Technische Universität Darmstadt, Darmstadt, Germany
| | - J Gehrunger
- Computer Systems Group, Department of Electrical Engineering and Information Technology, Technische Universität Darmstadt, Darmstadt, Germany
| | - C Hochberger
- Computer Systems Group, Department of Electrical Engineering and Information Technology, Technische Universität Darmstadt, Darmstadt, Germany
| | - T Oster
- Integrated Electronic Systems Lab, Department of Electrical Engineering and Information Technology, Technische Universität Darmstadt, Darmstadt, Germany
| | - K Hofmann
- Integrated Electronic Systems Lab, Department of Electrical Engineering and Information Technology, Technische Universität Darmstadt, Darmstadt, Germany
| | - J Suñé
- Departament d'Enginyeria Electrònica, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Valles, Spain
| | - E Miranda
- Departament d'Enginyeria Electrònica, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Valles, Spain
| | - L Alff
- Advanced Thin Film Technology Division, Institute of Materials Science, Technische Universität Darmstadt, Darmstadt, Germany
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Mahendra A, Murmu PP, Acharya SK, Islam A, Fiedler H, Gupta P, Granville S, Kennedy J. Shaping Perpendicular Magnetic Anisotropy of Co 2MnGa Heusler Alloy Using Ion Irradiation for Magnetic Sensor Applications. SENSORS (BASEL, SWITZERLAND) 2023; 23:s23094564. [PMID: 37177768 PMCID: PMC10181601 DOI: 10.3390/s23094564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 03/27/2023] [Accepted: 05/05/2023] [Indexed: 05/15/2023]
Abstract
Magnetic sensors are key elements in many industrial, security, military, and biomedical applications. Heusler alloys are promising materials for magnetic sensor applications due to their high spin polarization and tunable magnetic properties. The dynamic field range of magnetic sensors is strongly related to the perpendicular magnetic anisotropy (PMA). By tuning the PMA, it is possible to modify the sensing direction, sensitivity and even the accuracy of the magnetic sensors. Here, we report the tuning of PMA in a Co2MnGa Heusler alloy film via argon (Ar) ion irradiation. MgO/Co2MnGa/Pd films with an initial PMA were irradiated with 30 keV 40Ar+ ions with fluences (ions·cm-2) between 1 × 1013 and 1 × 1015 Ar·cm-2, which corresponds to displacement per atom values between 0.17 and 17, estimated from Monte-Carlo-based simulations. The magneto optical and magnetization results showed that the effective anisotropy energy (Keff) decreased from ~153 kJ·m-3 for the un-irradiated film to ~14 kJ·m-3 for the 1 × 1014 Ar·cm-2 irradiated film. The reduced Keff and PMA are attributed to ion-irradiation-induced interface intermixing that decreased the interfacial anisotropy. These results demonstrate that ion irradiation is a promising technique for shaping the PMA of Co2MnGa Heusler alloy for magnetic sensor applications.
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Affiliation(s)
- Anmol Mahendra
- Robinson Research Institute, Victoria University of Wellington, Wellington 6140, New Zealand
- National Isotope Centre, GNS Science, Lower Hutt 5010, New Zealand
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand
| | - Peter P Murmu
- National Isotope Centre, GNS Science, Lower Hutt 5010, New Zealand
| | - Susant Kumar Acharya
- Robinson Research Institute, Victoria University of Wellington, Wellington 6140, New Zealand
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand
| | - Atif Islam
- Robinson Research Institute, Victoria University of Wellington, Wellington 6140, New Zealand
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand
| | - Holger Fiedler
- National Isotope Centre, GNS Science, Lower Hutt 5010, New Zealand
| | - Prasanth Gupta
- National Isotope Centre, GNS Science, Lower Hutt 5010, New Zealand
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand
| | - Simon Granville
- Robinson Research Institute, Victoria University of Wellington, Wellington 6140, New Zealand
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand
| | - John Kennedy
- National Isotope Centre, GNS Science, Lower Hutt 5010, New Zealand
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand
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