Integrated miniature DC SQUID susceptometer for measuring properties of very small samples

Patent 4588947 Issued on May 13, 1986. Estimated Expiration Date:

December 30, 2003. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

Method and apparatus for balancing the magnetic field detecting loops of a cryogenic gradiometer using trimming coils and superconducting disks
Patent #: 4320341
Issued on: 03/16/1982
Inventor: Lutes

Apparatus for reducing low frequency noise in dc biased SQUIDS Patent #: 4389612
Issued on: 06/21/1983
Inventor: Simmonds , et al.

Inventor

Ketchen, Mark B.

Application

No. 06/567302 filed on 12/30/1983

US Classes:

324/201, Susceptibility257/31, Josephson257/34, Weak link (e.g., narrowed portion of superconductive line)324/248, Superconductive magnetometers327/527, Superconductive (e.g., cryogenic, etc.) device505/846Using superconductive quantum interference device (i.e., SQUID): (Class 324/248)

Examiners

Primary: Strecker, Gerard R.

Attorney, Agent or Firm

Stanland; Jackson E.

International Classes

G01R 33/16 (20060101)
G01R 33/035 (20060101)

Abstract

A miniature, fully integrated susceptometer capable of measuring the magnetic properties of very small samples (<10 μm) is described which is fabricated by thin film lithography on a single chip. The susceptometer is comprised of a dc SQUID including two series wired pick-up loops into which a sample to be measured can be placed. A field coil is provided which includes a separate single turn around each of the SQUID pick-up loops. The SQUID pick-up loops and the surrounding field coil turns are both located over a hole in a superconducting groundplane. The SQUID pick-up loops are connected by wide, low inductance transmission lines to remotely located Josephson tunnel junctions. The signal to be detected is generated locally within one of the SQUID pick-up loops to provide direct coupling of the sample to be measured to the SQUID pick-up loop. The SQUID tunnel junctions are remotely located from the pick-up loops and are located over a superconducting groundplane. A resistive balance circuit is provided, as is readout electronics for detecting the state of the SQUID.

Other References

McLachlan et al, "Detection Method for the . . . Phase Transition of 10μ Spheres, Rev. Sci. Inst., vol. 39, No. 9, Sep. 1968 pp. 1340-1342
Drukier et al, Transition Radiation Effects in Superconducting Granules Lettre al Nuevo Cimento, vol. 14, No. 8, Oct. 25, 1975, pp. 300-304
Hu et al, Experiments on Ge-Sn Barrier Josephson Junctions, IEEE Transactions on Magnetics, vol. MAG-15, No. 1, Jan. 1979, pp. 585-588
Ketchen et al, An Ultra-Low-Noise Tunnel Junction dc SQUID, Appl. Phys. Lett. 35(10), Nov. 15, 1979, pp. 81-84
Clarke, John, Advances in SQUID Magnetometers, IEEE Trans. on Electron Devices, vol. ED-27, No. 10, Oct. 1980, pp. 1898-1908
Ketchen et al, "Ultra-Low-Noise . . . dc SQUID with . . . Planar Input Coil" Appl. Phys. Lett. 40(8), Apr. 15, 1982, pp. 736-738
de Wall et al, Low Noise Niobium dc SQUID with a Planar Input Coil Appl. Phys. Lett. 42(4), Feb. 15, 1983, pp. 389-391
Muhlfelder et al, Double Transformer Coupling to a Very Low Noise SQUID, IEEE Trans. on Magnetics, vol. MAG-19, No. 3, May 1983, pp. 303-307
Voss et al, Niobium Nanobridge d.c. SQUID, Appl. Phys. Lett. 37(7), Oct. 1, 1980, pp. 656-658
Cromar et al, Low-Noise Tunnel Junction dc SQUID'S, Appl. Phys. Lett., 38(9), May 1, 1981, pp. 723-725
Ketchen et al, Superconducting Thin-Film Gradiometer, J. Appl. Phys. 49(7), Jul. 1978, pp. 4111-4116
Van Harlingen et al, "Superconducting . . . Device with Very Low Magnetic Flux Noise Energy, Appl. Phys. Lett. 41(2) Jul. 15, 1982, pp. 197-199