Albert Fert and Peter Grünberg discovered that this quantity depends on the magnetic field applied to iron chromide superlattices, leading to the development of spintronics. For 10 points each:
[10e] Name this quantity that equals voltage over current by Ohm’s law.
ANSWER: resistance [accept magnetoresistance or giant magnetoresistance; prompt on R]
[10m] Leo Esaki developed a type of these devices that achieves negative resistance due to quantum tunneling. On circuit diagrams, these devices are symbolized by a triangle pointing at a vertical line.
ANSWER: diodes [accept Esaki diodes]
[10h] In this effect, a “supercurrent” flows through a weak link at the junction between two superconductors. SQUIDs, which detect extremely small magnetic fields using this effect, are often used in dark matter detection experiments.
ANSWER: Josephson effect [accept Josephson junctions]
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