Reviews
To date, 7 review articles have been published. They are listed below in reverse chronological order.
2024
- Title
- SRF material research using muon spin rotation and beta-detected nuclear magnetic resonance
- Author
- T. Junginger, R. Laxdal, W. A. MacFarlane, A. Suter
- Journal
- Frontiers in Electronic Materials
- Volume
- 4
- Pages
- 1346235
- Year
- 2024
- Abstract
-
Muon spins precess in transverse magnetic fields and emit a positron preferentially in the spin direction at the instant of decay, enabling muon spin rotation (μSR) as a precise probe of local magnetic fields in matter. μSR has been used to characterize superconducting radio-frequency (SRF) materials since 2010. At TRIUMF, a beam of 4.2 MeV μ+ is implanted at a material-dependent depth of approximately 150 μm. A dedicated spectrometer was developed to measure the field of first vortex penetration and pinning strength in SRF materials in parallel magnetic fields of up to 300 mT. A low-energy beam available at PSI implants μ+ at variable depth in the London layer allowing for direct measurements of the London penetration depth from which other material parameters relevant for SRF applications, such as the lower critical field and the superheating field, can be calculated. Beta-detected nuclear magnetic resonance (β-NMR) is a technique similar to low-energy μSR using beams of low-energy β radioactive ions. With a recent upgrade, it is capable of detecting the penetration of parallel magnetic vortices, depth resolved with nanometer resolution at applied fields of up to 200 mT. In this paper, we review the impact and capabilities of these techniques for SRF research.
- 10.3389/femat.2024.1346235
2022
- Title
- Status and progress of ion-implanted βNMR at TRIUMF
- Author
- W. A. MacFarlane
- Journal
- Zeitschrift für Physikalische Chemie
- Volume
- 236
- Issue
- 6-8
- Pages
- 757-798
- Year
- 2022
- Abstract
-
Beta-detected NMR is a type of nuclear magnetic resonance that uses the asymmetric property of radioactive beta decay to provide a "nuclear" detection scheme. It is vastly more sensitive than conventional NMR on a per nuclear spin basis but requires a suitable radioisotope. I briefly present the general aspects of the method and its implementation at TRIUMF, where ion implantation of the NMR radioisotope is used to study a variety of samples including crystalline solids and thin films, and more recently, soft matter and even room temperature ionic liquids. Finally, I review the progress of the TRIUMF βNMR program in the period 2015-2021.
- 10.1515/zpch-2021-3154
2015
- Title
- Implanted-ion βNMR: a new probe for nanoscience
- Author
- W. A. MacFarlane
- Journal
- Solid State Nuclear Magnetic Resonance
- Volume
- 68-69
- Pages
- 1-12
- Year
- 2015
- Abstract
-
NMR detected by radioactive beta decay, β-NMR, is undergoing a renaissance largely due to the availability of high intensity low energy beams of the most common probe ion, 8Li+, and dedicated facilities for materials research. The radioactive detection scheme, combined with the low energy ion beam, enable depth resolved NMR measurements in crystals, thin films and multilayers on depth scales of 2-200 nm. After a brief historical introduction, technical aspects of implanted-ion β-NMR are presented, followed by a review of recent applications to a wide range of solids.
- 10.1016/j.ssnmr.2015.02.004
2013
- Title
- Recent progress with β-NMR at ISAC
- Author
- R. F. Kiefl, W. A. MacFarlane, K. H. Chow, G. D. Morris, C. D. P. Levy, M. R. Pearson
- Journal
- Nuclear Physics News
- Volume
- 23
- Issue
- 4
- Pages
- 29-32
- Year
- 2013
- Abstract
-
The ISAC facility at TRIUMF in Vancouver, Canada, produces intense beams of radioactive ions that are used in a broad research program encompassing fundamental properties of nuclei, nuclear astrophysics, medical physics, condensed matter physics, and physical chemistry. The focus of this article is on the latter subject and in particular recent developments in the use of β-detected NMR to probe electronic, magnetic, and structural properties of thin films and interfaces. Over the last 10 years considerable progress has been made developing the technique and applying it to current problems.
- 10.1080/10619127.2013.855575
2014
- Title
- β-NMR
- Author
- G. D. Morris
- Journal
- Hyperfine Interactions
- Volume
- 225
- Issue
- 1
- Pages
- 173-182
- Year
- 2014
- Abstract
-
The β-NMR facility at ISAC is constructed specifically for experiments in condensed matter physics with radioactive ion beams. Using co-linear optical pumping, a 8Li+ ion beam having a large nuclear spin polarisation and low energy (nominally 30 keV) can be generated. When implanted into materials these ions penetrate to shallow depths comparable to length scales of interest in the physics of surfaces and interfaces between materials. Such low-energy ions can be decelerated with simple electrostatic optics to enable depth-resolved studies of near-surface phenomena over the range of about 2-200 nm. Since the β-NMR signal is extracted from the asymmetry intrinsic to beta-decay and therefore monitors the polarisation of the radioactive probe nuclear magnetic moments, this technique is fundamentally a probe of local magnetism. More generally though, any phenomena which affects the polarisation of the implanted spins by, for example, a change in resonance frequency, line width or relaxation rate can be studied. The β-NMR program at ISAC currently supports a number of experiments in magnetism and superconductivity as well as novel ultra-thin heterostructures exhibiting properties that cannot occur in bulk materials. The general purpose zero/low field and high field spectrometers are configured to perform CW and pulsed RF nuclear magnetic resonance and spin relaxation experiments over a range of temperatures (3-300 K) and magnetic fields (0-9 T).
- 10.1007/s10751-013-0894-6
- Title
- Laser polarization facility
- Author
- C. D. P. Levy, M. R. Pearson, R. F. Kiefl, E. Mané, G. D. Morris, A. Voss
- Journal
- Hyperfine Interactions
- Volume
- 225
- Issue
- 1
- Pages
- 165
- Year
- 2014
- Abstract
-
An overview of the laser polarizer facility at ISAC is provided. The charge-exchange cell is described in some detail.
- 10.1007/s10751-013-0896-4
2005
- Title
- Application of low energy spin polarized radioactive ion beams in condensed matter research
- Author
- R. F. Kiefl, K. H. Chow, W. A. MacFarlane, G. D. Morris, C. D. P. Levy, Z. Salman
- Journal
- Nuclear Physics News
- Volume
- 15
- Issue
- 1
- Pages
- 26-32
- Year
- 2005
- Abstract
-
The new ISAC facility at TRIUMF (Canada), produces some of the world's most intense radioactive ion beams (RIBs). Although the primary scientific motivation for these facilities lies in nuclear physics and nuclear astrophysics, RIBs also have applications in condensed matter (CM). Many pioneering CM experiments have already been performed at the ISOLDE facility (CERN). Continuing on this path at ISAC we have recently polarized a beam of 8Li+ to be used as a magnetic probe of ultra-thin films and interfaces. We report here on progress in developing this new application of low energy RIBs, which is based on the technique of β-detected nuclear magnetic resonance (β-NMR).
- 10.1080/10506890500454592