title: Nanoelectronic primary thermometry below 4 mK.
abstract: Cooling nanoelectronic structures to millikelvin temperatures presents extreme challenges in maintaining thermal contact between the electrons in the device and an external cold bath. It is typically found that when nanoscale devices are cooled to ∼ 10 mK the electrons are significantly overheated. Here we report the cooling of electrons in nanoelectronic Coulomb blockade thermometers below 4 mK. The low operating temperature is attributed to an optimized design that incorporates cooling fins with a high electron-phonon coupling and on-chip electronic filters, combined with low-noise electronic measurements. By immersing a Coulomb blockade thermometer in the (3)He/(4)He refrigerant of a dilution refrigerator, we measure a lowest electron temperature of 3.7 mK and a trend to a saturated electron temperature approaching 3 mK. This work demonstrates how nanoelectronic samples can be cooled further into the low-millikelvin range.
authors.affiliation: Department of Physics, Lancaster University, Bailrigg, Lancaster LA1 4YB, UK.
authors.forename: D I
authors.initials: DI
authors.lastname: Bradley
authors.affiliation: Department of Physics, Lancaster University, Bailrigg, Lancaster LA1 4YB, UK.
authors.forename: R E
authors.initials: RE
authors.lastname: George
authors.affiliation: VTT Technical Research Centre of Finland, P.O. Box 1000, 02044 VTT Espoo, Finland.
authors.forename: D
authors.initials: D
authors.lastname: Gunnarsson
authors.affiliation: Department of Physics, Lancaster University, Bailrigg, Lancaster LA1 4YB, UK.
authors.forename: R P
authors.initials: RP
authors.lastname: Haley
authors.affiliation: VTT Technical Research Centre of Finland, P.O. Box 1000, 02044 VTT Espoo, Finland.
authors.forename: H
authors.initials: H
authors.lastname: Heikkinen
authors.affiliation: Department of Physics, Lancaster University, Bailrigg, Lancaster LA1 4YB, UK.|Lebedev Physical Institute, Moscow 119991, Russia.
authors.forename: Yu A
authors.initials: YA
authors.lastname: Pashkin
authors.affiliation: Aivon Oy, Valimotie 13A, 00380 Helsinki, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Penttilä
authors.affiliation: Department of Physics, Lancaster University, Bailrigg, Lancaster LA1 4YB, UK.
authors.forename: J R
authors.initials: JR
authors.lastname: Prance
authors.affiliation: VTT Technical Research Centre of Finland, P.O. Box 1000, 02044 VTT Espoo, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Prunnila
authors.affiliation: Lebedev Physical Institute, Moscow 119991, Russia.
authors.forename: L
authors.initials: L
authors.lastname: Roschier
authors.affiliation: Department of Physics, Lancaster University, Bailrigg, Lancaster LA1 4YB, UK.
authors.forename: M
authors.initials: M
authors.lastname: Sarsby
references.citation: Phys Rev Lett. 1994 Nov 21;73(21):2903-2906
references.pmid: 10057225
references.citation: Rev Sci Instrum. 2012 Aug;83(8):083903
references.pmid: 22938310
references.citation: Science. 2013 Mar 8;339(6124):1169-74
references.pmid: 23471399
references.citation: Phys Rev B Condens Matter. 1994 Mar 1;49(9):5942-5955
references.pmid: 10011570
references.citation: Rev Sci Instrum. 2011 May;82(5):053902
references.pmid: 21639513
references.citation: Phys Rev B Condens Matter. 1992 Oct 15;46(16):10339-10344
references.pmid: 10002878