Imaging selective magnetic patterning of Ti/LaMnO3/SrTiO3 heterostructures using scanning SQUID microscopy

Thijs Jasper Roskamp, Bart Folkers, Thies Jansen, Nicolas Gauquelin, Carlos Rosário, Hans Hilgenkamp

Research output: Contribution to conferencePosterAcademic

Abstract

In its bulk LaMnO3 (LMO) is an antiferromagnetic material, however thin films deposited on SrTiO3 (STO) substrates show ferromagnetism with a Curie temperature at 115 K [1]. Previous work from our group [2] has shown that there exists a critical thickness of 6 unit cells for LMO/STO heterostructures below which antiferromagnetism is recovered. This re-emergence has been clearly imaged using scanning SQUID microscopy (SSM), which is a powerful technique to image local magnetic flux by scanning a SQUID chip with micrometer scale resolution across the surface [3].
In this work we report the use of SSM to image the suppression of ferromagnetism by patterned Ti oxygen scavenging layers. A thin (~4nm) Ti layer covering a 20 unit cell LMO layer can completely suppress the magnetic signal emerging from the LMO layer. This suppression can be directly imaged using SSM where a clear reduction in stray magnetic field is measured for Ti covered LMO as opposed to uncovered regions. A possible reason for this reduction in ferromagnetism can be attributed to oxygen scavenging by the Ti layer, which mediate the indirect exchange processes that lead to ferromagnetism.
Furthermore, by selective patterning of Ti structures it is possible to effectively pattern the ferromagnetism down to the nanoscale. At structure sizes near 5 µm dipole-like magnetic signals are measured, typical of single ferromagnetic domains with an in-plane orientation. By introducing anisotropy in the patterned structures the dipole signals can be aligned and possibly interactions between them can be manipulated. This shows potential for control of ferromagnetism for applications in oxide electronics and spintronics.
The study also nicely exemplifies the power and potential of scanning SQUID microscopy to locally image magnetic signals, and our further developments on this will be discussed as well.

[1] Gupta et al. Applied Physics Letters 67: 3494-3496 (1995)
[2] Wang et al. Science 349: 716-719 (2015)
[3] Reith et al. Review of Scientific Instruments 88: 123706 (2017)
Original languageEnglish
Publication statusPublished - 5 Sept 2023
Event16th European Conference on Applied Superconductivity, EUCAS 2023 - Palazzo della Cultura e dei Congressi, Bologna, Italy
Duration: 3 Sept 20237 Sept 2023
Conference number: 16
https://eucas2023.esas.org/

Conference

Conference16th European Conference on Applied Superconductivity, EUCAS 2023
Abbreviated titleEUCAS 2023
Country/TerritoryItaly
CityBologna
Period3/09/237/09/23
Internet address

Keywords

  • scanning SQUID microscopy
  • LAMNO3
  • Magnetic patterning

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