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Magnetometer

About: Magnetometer is a research topic. Over the lifetime, 8672 publications have been published within this topic receiving 140654 citations.


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01 Jun 1972
TL;DR: In this paper, the authors present materials at the practical rather than theoretical level, allowing for a physical, quantitative, measurement-based understanding of magnetism among readers, be they professional engineers or graduate-level students.
Abstract: Introduction to Magnetic Materials, 2nd Edition covers the basics of magnetic quantities, magnetic devices, and materials used in practice. While retaining much of the original, this revision now covers SQUID and alternating gradient magnetometers, magnetic force microscope, Kerr effect, amorphous alloys, rare-earth magnets, SI Units alongside cgs units, and other up-to-date topics. In addition, the authors have added an entirely new chapter on information materials. The text presents materials at the practical rather than theoretical level, allowing for a physical, quantitative, measurement-based understanding of magnetism among readers, be they professional engineers or graduate-level students.

6,573 citations

Journal ArticleDOI
02 Oct 2008-Nature
TL;DR: This work shows how magneto-optical spin detection can be used to determine the location of a spin associated with a single nitrogen-vacancy centre in diamond with nanometre resolution under ambient conditions, and demonstrates the use of a single diamond spin as a scanning probe magnetometer to map nanoscale magnetic field variations.
Abstract: Magnetic resonance imaging and optical microscopy are key technologies in the life sciences. For microbiological studies, especially of the inner workings of single cells, optical microscopy is normally used because it easily achieves resolution close to the optical wavelength. But in conventional microscopy, diffraction limits the resolution to about half the wavelength. Recently, it was shown that this limit can be partly overcome by nonlinear imaging techniques, but there is still a barrier to reaching the molecular scale. In contrast, in magnetic resonance imaging the spatial resolution is not determined by diffraction; rather, it is limited by magnetic field sensitivity, and so can in principle go well below the optical wavelength. The sensitivity of magnetic resonance imaging has recently been improved enough to image single cells, and magnetic resonance force microscopy has succeeded in detecting single electrons and small nuclear spin ensembles. However, this technique currently requires cryogenic temperatures, which limit most potential biological applications. Alternatively, single-electron spin states can be detected optically, even at room temperature in some systems. Here we show how magneto-optical spin detection can be used to determine the location of a spin associated with a single nitrogen-vacancy centre in diamond with nanometre resolution under ambient conditions. By placing these nitrogen-vacancy spins in functionalized diamond nanocrystals, biologically specific magnetofluorescent spin markers can be produced. Significantly, we show that this nanometre-scale resolution can be achieved without any probes located closer than typical cell dimensions. Furthermore, we demonstrate the use of a single diamond spin as a scanning probe magnetometer to map nanoscale magnetic field variations. The potential impact of single-spin imaging at room temperature is far-reaching. It could lead to the capability to probe biologically relevant spins in living cells.

1,814 citations

Journal ArticleDOI
TL;DR: In this article, the basic principles of modern optical magnetometers, discuss fundamental limitations on their performance, and describe recently explored applications for dynamical measurements of biomagnetic fields, detecting signals in NMR and MRI, inertial rotation sensing, magnetic microscopy with cold atoms, and tests of fundamental symmetries of nature.
Abstract: Some of the most sensitive methods of measuring magnetic fields use interactions of resonant light with atomic vapour. Recent developments in this vibrant field have led to improvements in sensitivity and other characteristics of atomic magnetometers, benefiting their traditional applications for measurements of geomagnetic anomalies and magnetic fields in space, and opening many new areas previously accessible only to magnetometers based on superconducting quantum interference devices. We review basic principles of modern optical magnetometers, discuss fundamental limitations on their performance, and describe recently explored applications for dynamical measurements of biomagnetic fields, detecting signals in NMR and MRI, inertial rotation sensing, magnetic microscopy with cold atoms, and tests of fundamental symmetries of nature.

1,489 citations

Journal ArticleDOI
TL;DR: The magnetic field experiment on WIND will provide data for studies of a broad range of scales of structures and fluctuation characteristics of the interplanetary magnetic field throughout the mission, and, where appropriate, relate them to the statics and dynamics of the magnetosphere.
Abstract: The magnetic field experiment on WIND will provide data for studies of a broad range of scales of structures and fluctuation characteristics of the interplanetary magnetic field throughout the mission, and, where appropriate, relate them to the statics and dynamics of the magnetosphere. The basic instrument of the Magnetic Field Investigation (MFI) is a boom-mounted dual triaxial fluxgate magnetometer and associated electronics. The dual configuration provides redundancy and also permits accurate removal of the dipolar portion of the spacecraft magnetic field. The instrument provides (1) near real-time data at nominally one vector per 92 s as key parameter data for broad dissemination, (2) rapid data at 10.9 vectors s−1 for standard analysis, and (3) occasionally, snapshot (SS) memory data and Fast Fourier Transform data (FFT), both based on 44 vectors s−1. These measurements will be precise (0.025%), accurate, ultra-sensitive (0.008 nT/step quantization), and where the sensor noise level is <0.006 nT r.m.s. for 0–10 Hz. The digital processing unit utilizes a 12-bit microprocessor controlled analogue-to-digital converter. The instrument features a very wide dynamic range of measurement capability, from ±4 nT up to ±65 536 nT per axis in eight discrete ranges. (The upper range permits complete testing in the Earth's field.) In the FTT mode power spectral density elements are transmitted to the ground as fast as once every 23 s (high rate), and 2.7 min of SS memory time series data, triggered automatically by pre-set command, requires typically about 5.1 hours for transmission. Standard data products are expected to be the following vector field averages: 0.0227-s (detail data from SS), 0.092 s (‘detail’ in standard mode), 3 s, 1 min, and 1 hour, in both GSE and GSM coordinates, as well as the FFT spectral elements. As has been our team's tradition, high instrument reliability is obtained by the use of fully redundant systems and extremely conservative designs. We plan studies of the solar wind: (1) as a collisionless plasma laboratory, at all time scales, macro, meso and micro, but concentrating on the kinetic scale, the highest time resolution of the instrument (=0.022 s), (2) as a consequence of solar energy and mass output, (3) as an external source of plasma that can couple mass, momentum, and energy to the Earth's magnetosphere, and (4) as it is modified as a consequence of its imbedded field interacting with the moon. Since the GEOTAIL Inboard Magnetometer (GIM), which is similar to the MFI instrument, was developed by members of our team, we provide a brief discussion of GIM related science objectives, along with MFI related science goals.

1,368 citations

Journal ArticleDOI
10 Apr 2003-Nature
TL;DR: A new spin-exchange relaxation-free (SERF) atomic magnetometer is described, and theoretical analysis shows that fundamental sensitivity limits of this device are below 0.01 fT Hz-1/2, which would enable new applications, including the possibility of mapping non-invasively the cortical modules in the brain.
Abstract: The magnetic field is one of the most fundamental and ubiquitous physical observables, carrying information about all electromagnetic phenomena. For the past 30 years, superconducting quantum interference devices (SQUIDs) operating at 4 K have been unchallenged as ultrahigh-sensitivity magnetic field detectors, with a sensitivity reaching down to 1 fT Hz(-1/2) (1 fT = 10(-15) T). They have enabled, for example, mapping of the magnetic fields produced by the brain, and localization of the underlying electrical activity (magnetoencephalography). Atomic magnetometers, based on detection of Larmor spin precession of optically pumped atoms, have approached similar levels of sensitivity using large measurement volumes, but have much lower sensitivity in the more compact designs required for magnetic imaging applications. Higher sensitivity and spatial resolution combined with non-cryogenic operation of atomic magnetometers would enable new applications, including the possibility of mapping non-invasively the cortical modules in the brain. Here we describe a new spin-exchange relaxation-free (SERF) atomic magnetometer, and demonstrate magnetic field sensitivity of 0.54 fT Hz(-1/2) with a measurement volume of only 0.3 cm3. Theoretical analysis shows that fundamental sensitivity limits of this device are below 0.01 fT Hz(-1/2). We also demonstrate simple multichannel operation of the magnetometer, and localization of magnetic field sources with a resolution of 2 mm.

1,238 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023535
2022967
2021303
2020392
2019411
2018407