title: An ultra-low temperature scanning Hall probe microscope for magnetic imaging below 40 mK.
abstract: We describe the design of a low temperature scanning Hall probe microscope (SHPM) for a dilution refrigerator system. A detachable SHPM head with 25.4 mm OD and 200 mm length is integrated at the end of the mixing chamber base plate of the dilution refrigerator insert (Oxford Instruments, Kelvinox MX-400) by means of a dedicated docking station. It is also possible to use this detachable SHPM head with a variable temperature insert (VTI) for 2 K-300 K operations. A microfabricated 1μm size Hall sensor (GaAs/AlGaAs) with integrated scanning tunneling microscopy tip was used for magnetic imaging. The field sensitivity of the Hall sensor was better than 1 mG/√Hz at 1 kHz bandwidth at 4 K. Both the domain structure and topography of LiHoF4, which is a transverse-field Ising model ferromagnet which orders below TC = 1.53 K, were imaged simultaneously below 40 mK.
authors.affiliation: NanoMagnetics Instruments Ltd., Hacettepe - İvedik OSB Teknokent, 1368. Cad., No: 61/33, 06370 Yenimahalle, Ankara, Turkey.
authors.forename: Özgür
authors.initials: Ö
authors.lastname: Karcı
authors.affiliation: Laboratory for Quantum Magnetism, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Julian O
authors.initials: JO
authors.lastname: Piatek
authors.affiliation: Laboratory for Quantum Magnetism, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Pau
authors.initials: P
authors.lastname: Jorba
authors.affiliation: NanoMagnetics Instruments Ltd., Hacettepe - İvedik OSB Teknokent, 1368. Cad., No: 61/33, 06370 Yenimahalle, Ankara, Turkey.
authors.forename: Münir
authors.initials: M
authors.lastname: Dede
authors.affiliation: Laboratory for Quantum Magnetism, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Henrik M
authors.initials: HM
authors.lastname: Rønnow
authors.affiliation: Department of Physics, Middle East Technical University, 06800 Ankara, Turkey.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Oral