Meissner effect

Meissner effect
Piotr Jaworski, PioM EN DE PL; POLAND/Poznań · Public domain · source
Name	Meissner effect
Discovered	1933
Discoverers	Walther Meissner; Robert Ochsenfeld
Field	Condensed matter physics; Low-temperature physics
Related	Superconductivity; Type I superconductor; Type II superconductor

Meissner effect The Meissner effect is the phenomenon in which a superconducting material expels magnetic flux when cooled below its critical temperature, producing perfect diamagnetism and zero internal magnetic field. It is a defining macroscopic signature distinguishing superconductors from perfect conductors and underpins many experimental tests and technological applications across cryogenics, materials science, and electrical engineering.

Introduction

The Meissner effect was reported by Walther Meissner and Robert Ochsenfeld in 1933 and quickly became central to the theoretical development by researchers such as Hendrik Lorentz, Lev Landau, Fritz London, Fritz London (London brothers), and John Bardeen. Its recognition informed the formulation of models including the London equations, the Ginzburg–Landau theory developed by Lev Landau and Vitaly Ginzburg, and the microscopic BCS theory by John Bardeen, Leon Cooper, and Robert Schrieffer. Experimentalists at institutions like the University of Munich, Bell Laboratories, Kamerlingh Onnes Laboratory, and the Royal Society used the effect to validate materials such as lead, mercury, niobium, and later high-temperature cuprate and iron-based superconductors discovered by Alex Müller, Georg Bednorz, and others.

Physical explanation and theory

The microscopic origin of the Meissner effect is explained in BCS theory by formation of Cooper pairs (Cooper pair) mediated by electron–phonon interactions described by Lev Davidovich Landau and Bardeen, Cooper, and Schrieffer. Phenomenological descriptions include the London brothers’ London equations and the Ginzburg–Landau model introduced by Vitaly Ginzburg and Lev Landau. The penetration depth and coherence length, key length scales introduced by Lev Landau and Vitaly Ginzburg, determine whether a material is a Type I superconductor classified by Abrikosov or a Type II superconductor studied by Alexei Abrikosov. Magnetic flux quantization was predicted by Fritz London and later observed in experiments influenced by researchers such as Brian Josephson and Philip Anderson. Theoretical frameworks incorporate symmetry concepts from Emmy Noether and topological ideas later advanced by Michael Berry and Frank Wilczek in related contexts.

Experimental observation and measurement

Early measurements by Meissner and Ochsenfeld used magnetometers and low-temperature setups similar to those at Kamerlingh Onnes Laboratory; later techniques employed SQUIDs developed at IBM and universities, vibrating sample magnetometers used in laboratories such as Oak Ridge National Laboratory and Lawrence Berkeley National Laboratory, and muon spin rotation experiments at facilities like Rutherford Appleton Laboratory and Paul Scherrer Institute. Precision tests have been carried out by teams at Massachusetts Institute of Technology, Stanford University, Max Planck Institute, and CERN using cryostats from companies like Oxford Instruments. Measurements probe the London penetration depth via microwave resonators and tunnel-diode oscillators in collaborations involving Bell Labs, Los Alamos National Laboratory, and National Institute of Standards and Technology. Neutron scattering studies at Institut Laue–Langevin and synchrotron techniques at Deutsches Elektronen–Synchrotron map vortex lattices in Type II superconductors explored by groups at University of Cambridge and École Normale Supérieure.

Types of superconductors and variations

Type I superconductors such as aluminium, lead, and mercury exhibit complete Meissner expulsion up to a critical field studied by laboratories including Argonne National Laboratory and Pennsylvania State University. Type II superconductors including niobium–tin, niobium, yttrium barium copper oxide discovered by Paul Chu and Matthias, and iron pnictides discovered by Hosono allow partial flux penetration in the mixed state forming Abrikosov vortices, work influenced by Alexei Abrikosov and Vitaly Ginzburg. Variations include unconventional pairing in heavy-fermion compounds investigated at University of Tokyo and Cambridge, organic superconductors studied at Kyoto University, and topological superconductors researched by Microsoft Station Q and Princeton University. Granular, proximity-effect, and thin-film superconductivity have been characterized by teams at IBM, Tohoku University, and Harvard University, with heterostructures probed for Majorana modes by researchers at Delft University of Technology and University of California, Berkeley.

Applications and technological implications

The Meissner effect enables magnetic levitation showcased by maglev prototypes developed by Central Japan Railway Company and demonstrations at universities such as MIT and ETH Zurich. It underlies MRI magnets manufactured by General Electric and Siemens Healthineers, particle accelerator cavities at CERN and DESY, and superconducting quantum interference devices (SQUIDs) used by NASA and the National Institutes of Health. Superconducting magnets in fusion experiments at ITER and Tokamak projects rely on Meissner-related behavior in niobium-based alloys developed at companies like Mitsubishi Heavy Industries and European consortiums. Quantum computing platforms from Google Quantum AI, IBM Quantum, and Rigetti leverage superconducting circuits whose coherence properties are influenced by flux expulsion, while power applications in superconducting cables and fault current limiters have been pursued by American Superconductor and Nexans.

Historical discovery and significance

The 1933 discovery at the University of Munich by Walther Meissner and Robert Ochsenfeld prompted theoretical responses from prominent physicists including the London brothers, Lev Landau, and John Bardeen, shaping 20th-century condensed matter physics at institutions like Bell Labs and Cambridge. That work influenced Nobel-recognized advances: Lev Landau (Nobel context), John Bardeen (Nobel Prize), Alex Müller (Nobel Prize), and others whose discoveries altered industries represented by Siemens, IBM, and General Electric. The Meissner effect remains a cornerstone linking experimental platforms at Brookhaven National Laboratory, Rutherford Appleton Laboratory, and Los Alamos National Laboratory with theoretical developments from institutions such as Caltech, Columbia University, and the Max Planck Society, continuing to guide materials discovery, cryogenic engineering, and quantum technology research.

Category:Superconductivity