John C. Mallinson (30 January 1932 – 24 December 2015) was a British physicist who made significant contributions to the understanding of

magnetism Magnetism is the class of physical attributes that are mediated by a magnetic field, which refers to the capacity to induce attractive and repulsive phenomena in other entities. Electric currents and the magnetic moments of elementary particles ...

and

magnetic recording Magnetic storage or magnetic recording is the storage of data on a magnetized medium. Magnetic storage uses different patterns of magnetisation in a magnetizable material to store data and is a form of non-volatile memory. The information is ac ...

. He is perhaps best remembered for his theoretical work on structures with one-sided magnetic flux.J.C. Mallinson, "One-sided Fluxes - A Magnetic Curiosity?", IEEE Trans. Magn., Vol. MAG-9, No. 4, Dec. 1973, pp. 678-682
/ref> Their use is exemplified in the

Halbach array A Halbach array is a special arrangement of permanent magnets that augments the magnetic field on one side of the array while cancelling the field to near zero on the other side. This is achieved by having a spatially rotating pattern of magn ...

and in the familiar

refrigerator magnet A refrigerator magnet or fridge magnet is a small magnet, often attached to an artistic or whimsical ornament, which may be used to post items such as shopping lists, Christmas cards, child art or reminders on a refrigerator door, or which simp ...

Personal life

Mallinson was born on 30 January 1932 in Bradford, Yorkshire, UK. He attended

University College, Oxford University College (in full The College of the Great Hall of the University of Oxford, colloquially referred to as "Univ") is a constituent college of the University of Oxford in England. It has a claim to being the oldest college of the univer ...

and graduated in 1953 with BA and MA degrees in Natural Philosophy (physics), and an honorary doctorate in 1997. On graduating, he joined the

Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) and ...

for a 3-year term, advancing to pilot a

Canberra bomber The English Electric Canberra is a British first-generation, jet-powered medium bomber. It was developed by English Electric during the mid- to late 1940s in response to a 1944 Air Ministry requirement for a successor to the wartime de Havil ...

.Computer History Museum: J. C. Mallinson, "Recollections", 2011
/ref> He remained interested in aviation, and practiced

aerobatics Aerobatics is the practice of flying maneuvers involving aircraft attitudes that are not used in conventional passenger-carrying flights. The term is a portmanteau of "aerial" and "acrobatics". Aerobatics are performed in aeroplanes and glid ...

over

Half Moon Bay, California Half Moon Bay is a coastal city in San Mateo County, California, United States, approximately south of San Francisco. Its population was 11,795 as of the 2020 census. Immediately at the north of Half Moon Bay is Pillar Point Harbor and the un ...

. He volunteered at the Hiller Air Museum at the

San Carlos, California San Carlos (Spanish for "St. Charles") is a city in San Mateo County, California, United States. The population is 30,722 per the 2020 census. History Native Americans Prior to the Spanish arrival in 1769, the land of San Carlos was occupi ...

, airport.John Mallinson Obituary, Magnetics Society Newsletter, Vol. 56, No. 2, Apr. 2016, page 6
/ref> Mallinson died in December 2015 following a stroke. He had two daughters, Caroline and Elizabeth and several grandchildren.

Career

In 1956, Mallinson emigrated to the United States to join

AMP Incorporated TE Connectivity is an American Swiss-domiciled technology company that designs and manufactures connectors and sensors for several industries, such as automotive, industrial equipment, data communication systems, aerospace, defense, medical, o ...

Harrisburg, Pennsylvania Harrisburg is the capital city of the Commonwealth of Pennsylvania, United States, and the county seat of Dauphin County. With a population of 50,135 as of the 2021 census, Harrisburg is the 9th largest city and 15th largest municipality in Pe ...

, where he studied the magnetic properties of

ferrites Ferrite may refer to: * Ferrite (iron), one of the allotropes of iron that is stable at room temperature and pressure, α-Fe * Ferrite (magnet), a ferrimagnetic ceramic material Ferrite family, a Spanish family that has members all over the world. ...

. In 1962, he moved to the west coast to join Ampex Corporation in

Redwood City, California Redwood City is a city on the San Francisco Peninsula in Northern California's Bay Area, approximately south of San Francisco, and northwest of San Jose. Redwood City's history spans its earliest inhabitation by the Ohlone people to being a ...

, rising to become the director of the Recording Technology Department. The department included other major contributors in magnetic recording such as Charles Coleman and

Neal Bertram Neal Bertram is a physicist noted for his contributions to the theory of magnetic recording. From 1968 to 1985, he worked for Ampex Corporation in Redwood City. From 1985 to 2004, he was an Endowed Chair Professor at the Center for Memory and ...

. Mallinson was called upon as an expert in the long term archival properties of magnetic tape. Also at Ampex, Mallinson developed the theory for structures with one-sided magnetic flux. One such structure is the

Halbach Array A Halbach array is a special arrangement of permanent magnets that augments the magnetic field on one side of the array while cancelling the field to near zero on the other side. This is achieved by having a spatially rotating pattern of magn ...

which provides a means of generating powerful, well-confined magnetic fields with

permanent magnets A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, ...

. The familiar decorative

also takes advantage of one-sided flux. Also at Ampex, Mallinson oversaw the development of

PRML In computer data storage, partial-response maximum-likelihood (PRML) is a method for recovering the digital data from the weak analog read-back signal picked up by the head of a magnetic disk drive or tape drive. PRML was introduced to recover dat ...

, a new readback technique for magnetic recording. In 1984, Mallinson left Ampex to become the founding director of the new Center for Magnetic Recording Research (CMRR) at

UC San Diego The University of California, San Diego (UC San Diego or colloquially, UCSD) is a public university, public Land-grant university, land-grant research university in San Diego, California. Established in 1960 near the pre-existing Scripps Insti ...

. He was appointed adjunct professor in 1987. By 1990, the Center boasted eight professors and 36 graduate students. Upon leaving CMRR in 1990, Mallinson taught a course on Magnetism and Magnetic Recording and also took advantage of teaching and research opportunities overseas. In 1993 and 1995, Mallinson was a visiting professor at

KTH Royal Institute of Technology The KTH Royal Institute of Technology ( sv, Kungliga Tekniska högskolan, lit=Royal Institute of Technology), abbreviated KTH, is a public research university in Stockholm, Sweden. KTH conducts research and education in engineering and technolo ...

in Stockholm, Sweden and was appointed permanent visiting professor in 1996. In 1994, he was a visiting professor at the

University of Twente The University of Twente (Dutch: ''Universiteit Twente''; , abbr. ) is a public technical university located in Enschede, Netherlands. The university has been placed in the top 170 universities in the world by multiple central ranking tables. ...

Enschede Enschede (; known as in the local Twents dialect) is a municipality and city in the eastern Netherlands in the province of Overijssel and in the Twente region. The eastern parts of the urban area reaches the border of the German city of Gronau ...

The Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...

. Also in 1996, he was a distinguished visiting professor,

Sony , commonly stylized as SONY, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. As a major technology company, it operates as one of the world's largest manufacturers of consumer and professional ...

Sabbatical Chair in

Yokohama is the second-largest city in Japan by population and the most populous municipality of Japan. It is the capital city and the most populous city in Kanagawa Prefecture, with a 2020 population of 3.8 million. It lies on Tokyo Bay, south of To ...

, Japan. From 1998 through 2005, he was a regular visiting professor at

Plymouth University The University of Plymouth is a public research university based predominantly in Plymouth, England, where the main campus is located, but the university has campuses and affiliated colleges across South West England. With students, it is the ...

, UK, where he collaborated with Hazel Shute and David Wilton. In particular they were able to extend the 2D one-sided flux configurations into 3-dimensions.

Books

Mallinson is the author of four textbooks: * “The Foundations of Magnetic Recording", Academic Press (1987) * “The Foundations of Magnetic Recording:, Academic Press (2nd edition, 1993), Maruzen Publishing (Japanese edition) (September 1994) * “Magneto-Resistive Heads, Fundamentals and Applications", Academic Press (1996), Maruzen Publishing (Japanese edition) (September 1996) * "Magneto-Resistive and Spin Valve Heads: Fundamentals and Applications (Electromagnetism)", Academic Press; 2nd edition (September 2001), Maruzen Publishing (Japanese edition) (June 2002) * "Recollections", a collection of short autobiographical stories, unpublished, 2011 Mallinson has published many scientific papers and several contributed book chapters.

Honours and awards

Mallinson became a

Fellow of the IEEE The Institute of Electrical and Electronics Engineers (IEEE) is a 501(c)(3) professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operation ...

in 1982 for "contributions to the theory of magnetic recording". He was selected as the

IEEE Magnetics Society The Institute of Electrical and Electronics Engineers (IEEE) is a 501(c)(3) professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operati ...

Distinguished Lecturer for 1983-4 on the topic of "The Next Decade in Magnetic Recording". In 1984, he was awarded the

Alexander M. Poniatoff Alexander Matveevich Poniatoff (russian: Александр Матвеевич Понятов, tr. ''Aleksándr Matvéjevič Ponjatóv''; 25 March 1892 – 24 October 1980) was an American electrical engineer. Poniatoff was born in 1892 in Russkay ...

Golden Achievement Award for "leadership in the theory and practice of magnetic recording"."Mallinson receives Ampex's highest award", Ampex Amplifier (magazine), Summer 1984 In 1997, he was bestowed with a

Doctor of Science Doctor of Science ( la, links=no, Scientiae Doctor), usually abbreviated Sc.D., D.Sc., S.D., or D.S., is an academic research degree awarded in a number of countries throughout the world. In some countries, "Doctor of Science" is the degree used f ...

degree from

Oxford University Oxford () is a city in England. It is the county town and only city of Oxfordshire. In 2020, its population was estimated at 151,584. It is north-west of London, south-east of Birmingham and north-east of Bristol. The city is home to the ...

. In 2007, he received the

Achievement Award for "contributions to the theory, practice and teaching of magnetic recording"IEEE Magnetics Society Achievement Award: John C. Mallinson
/ref>

References

{{DEFAULTSORT:Mallinson, John C. 20th-century American physicists Fellow Members of the IEEE 1932 births 2015 deaths English physicists Scientists from Bradford People from Ojai, California British textbook writers English emigrants to the United States Alumni of University College, Oxford 20th-century British physicists American textbook writers 20th-century British male writers 20th-century American male writers