View source for Leo Esaki

{{Short description|Japanese solid-state physicist (born 1925)}}
{{Use mdy dates|date=April 2024}}
{{Infobox person
| name              = Leo Esaki
| native_name       = 江崎 玲於奈
| native_name_lang  = ja
| image = Esaki_leo_Gakushiin.jpg
| caption           = Portrait photograph released by the [[Japan Academy]].
| birth_date        = {{Birth date and age|1925|03|12}}
| birth_place       = [[Osaka]], [[Empire of Japan]]
| death_date        = <!--{{Death date and age |YYYY|MM|DD|YYYY|MM|DD}} (death date then birth date)-->
| death_place       = 
| education         = [[Third Higher School]]
| alma_mater        = [[University of Tokyo|Tokyo Imperial University]] ([[Bachelor of Science|BS]], [[Doctor of Philosophy|PhD]])
| known_for         = {{Plain list|
* [[Quantum tunnelling|Tunneling]] in [[semiconductor]]s
* [[Tunnel diode]]
* [[Superlattice]]s
}}
| awards            = {{Plain list|
* [[Nishina Memorial Prize]] (1959)
* [[IRE Morris Liebmann Memorial Prize]] (1961)
* [[Stuart Ballantine Medal]] (1961)
* [[Nobel Prize in Physics]] (1973)
* [[International Prize for New Materials]] (1985)
* [[Harold Pender Award]] (1989)
* [[IEEE Medal of Honor]] (1991)
* [[Japan Prize]] (1998)
}}
| module={{Infobox scientist|embed=yes
| title             = [[IBM Fellow]] (1967–1992)
| fields            = [[Solid-state physics]]
| work_institutions = {{Plain list| 
* [[Sony|Tokyo Tsushin Kogyo]] (1956–1960)
* [[Thomas J. Watson Research Center]] (1960–1992)
}}
}}
}}

'''Leo Esaki''' ({{IPAc-en|ɪ|ˈ|s|ɑː|k|i}} {{Respell|ih|SAH|kee}};<ref>{{Cite web|title=Esaki|url=https://www.dictionary.com/browse/esaki|url-status=live|publisher=[[Dictionary.com]]|archive-url=https://web.archive.org/web/20250607153523/https://www.dictionary.com/browse/esaki|archive-date=2025-06-07|access-date=2025-06-07}}</ref> {{Langx|ja|江崎 玲於奈|Esaki Reona}}; born March 12, 1925) is a Japanese [[solid-state physicist]] who shared the 1973 [[Nobel Prize in Physics]] with [[Ivar Giaever]] and [[Brian Josephson]] for his work on [[Quantum tunnelling|tunneling]] in [[semiconductor]]s, which led to his invention of the [[tunnel diode]] that exploits this phenomenon. His research was done when he was with [[Sony]]. He has also contributed in being a pioneer of semiconductor [[superlattice]]s.

== Biography ==
Leo Esaki was born on March 12, 1925, in [[Osaka]], Japan,<ref name=NobelFacts>{{Cite web|title=Leo Esaki – Facts|url=https://www.nobelprize.org/prizes/physics/1973/esaki/facts/|url-status=live|publisher=[[Nobel Foundation]]|archive-url=https://web.archive.org/web/20250703204634/https://www.nobelprize.org/prizes/physics/1973/esaki/facts/|archive-date=2025-07-03|access-date=2025-10-27}}</ref> and grew up in [[Kyoto]], where he attended the [[Third Higher School]]. He then went on to study physics at Tokyo Imperial University (now the [[University of Tokyo]]), graduating with a [[B.S.]] in 1947.<ref name=jp>{{Cite web|title=Dr. Leo Esaki|url=http://www.japanprize.jp/en/prize_prof_1998_esaki.html|url-status=live|publisher=Japan Prize Foundation|archive-url=https://web.archive.org/web/20250827140325/https://www.japanprize.jp/en/prize_prof_1998_esaki.html|archive-date=2025-08-27}}</ref>

=== Sony ===
[[File:Leo Esaki 1959b.jpg|thumb|Esaki works at [[Sony]], June 1959]]

In 1956, Esaki became chief physicist at Tokyo Tsushin Kogyo (now [[Sony]]).<ref>{{Cite web|title=Leo Esaki|url=https://www.britannica.com/biography/Leo-Esaki|url-status=live|publisher=[[Britannica]]|archive-url=https://web.archive.org/web/20250813042151/https://www.britannica.com/biography/Leo-Esaki|archive-date=2025-08-13|access-date= 2025-08-16}}</ref>

In 1958, Esaki recognized that when the [[p–n junction]] width of [[germanium]] is thinned, the [[current–voltage characteristic]] is dominated by the influence of the [[Quantum tunnelling|tunnel effect]]—and, as a result, he discovered that as the voltage is increased, the current decreases inversely—indicating [[negative resistance]].<ref>{{Cite journal| first1 = L.| title = New Phenomenon in Narrow Germanium p-n Junctions| url = https://archive.org/details/sim_physical-review_1958-01-15_109_2/page/602| last1 = Esaki| journal = Physical Review| volume = 109| issue = 2| pages = 603| year = 1958 | doi = 10.1103/PhysRev.109.603|bibcode = 1958PhRv..109..603E }}</ref> This discovery was the first demonstration of solid tunneling effects in physics, and it was the birth of a new electronic device called the [[tunnel diode]] (or Esaki diode), the first quantum electronic device in history. He received a [[Ph.D.]] from Tokyo Imperial University due to this breakthrough invention in 1959.<ref name=jp/>

In 1973, Esaki was awarded the [[Nobel Prize in Physics]] for this work.<ref>Esaki, Leo, "Long Journey into Tunneling," [http://nobelprize.org/nobel_prizes/physics/laureates/1973/esaki-lecture.html Nobel Lecture], December 12, 1973.</ref> He became the first Nobel laureate to receive the Prize from [[King Carl XVI Gustaf]] of Sweden.

=== IBM ===
In 1960, Esaki moved to the United States and joined [[IBM]]'s [[Thomas J. Watson Research Center]], where he was appointed an [[IBM Fellow]] in 1967.<ref>{{Cite web|title=Leo Esaki – Biographical|url=https://www.nobelprize.org/prizes/physics/1973/esaki/biographical/|url-status=live|publisher=[[Nobel Foundation]]|archive-url=https://web.archive.org/web/20250831224440/https://www.nobelprize.org/prizes/physics/1973/esaki/biographical/|archive-date=2025-08-31|access-date=2025-08-16}}</ref> 

In 1970, Esaki predicted that semiconductor [[superlattices]] will be formed to induce a differential negative-resistance effect via an artificially one-dimensional periodic structural changes in semiconductor crystals.<ref>{{cite journal|doi=10.1147/rd.141.0061|title=Superlattice and Negative Differential Conductivity in Semiconductors|year=1970|last1=Esaki|first1=L.|last2=Tsu|first2=R.|journal=IBM Journal of Research and Development|volume=14|pages=61–65}}</ref> His unique "molecular beam epitaxy" thin-film crystal growth method can be regulated quite precisely in ultrahigh vacuum. A 1987 comment by Esaki regarding the original paper notes:
<blockquote>
"The original version of the paper was rejected for publication by ''[[Physical Review]]'' on the referee's unimaginative assertion that it was 'too speculative' and involved 'no new physics.' However, this proposal was quickly accepted by the Army Research Office..."<ref>"This Weeks's Citation Classic", ''[[Current Contents]]'' No 28, July 13, 1987.</ref>
</blockquote>

In 1972, Esaki realized his concept of superlattices in III-V group semiconductors. Later, this concept influenced many fields like metals and magnetic materials.

=== Later life ===
In 1992, Esaki returned to Japan, where he subsequently served as President of the [[University of Tsukuba]]<ref name=jp /> and of the [[Shibaura Institute of Technology]]. Since 2006, he is President of [[Yokohama College of Pharmacy]].

Since the death of [[Yoichiro Nambu]] in 2015, Esaki is the oldest [[Japanese Nobel laureate]].

== Esaki's "five don'ts" rules ==
At the 1994 [[Lindau Nobel Laureate Meetings]], Esaki suggested a list of "five don'ts" which anyone in realizing his creative potential should follow. Two months later,  the chairman of the Nobel Committee for Physics [[Carl Nordling]] incorporated the rules in his own speech.<ref>{{cite journal|doi=10.1088/0031-8949/1995/T59/001|bibcode=1995PhST...59...21N|url=https://web.stanford.edu/~rotundu/documents/how_to_get_it.pdf|title=How to get the Nobel Prize in physics|year=1995|last1=Nordling|first1=Carl|journal=Physica Scripta|volume=59|pages=21–25|s2cid=250817314 }}</ref>
#Don't allow yourself to be trapped by your past experiences.
#Don't allow yourself to become overly attached to any one authority in your field – the great professor, perhaps.
#Don't hold on to what you don't need.
#Don't avoid confrontation.
#Don't forget your spirit of childhood curiosity.

== Recognition ==
In recognition of three Nobel laureates' contributions, the bronze statues of [[Shin'ichirō Tomonaga]], Leo Esaki, and [[Makoto Kobayashi (physicist)|Makoto Kobayashi]] were set up in the Central Park of Azuma 2 in [[Tsukuba]] in 2015.<ref>{{Cite web|url=http://mainichi.jp/feature/news/m20150316ddlk08040111000c.html|archive-url=https://web.archive.org/web/20150424074404/http://mainichi.jp/feature/news/m20150316ddlk08040111000c.html|url-status=dead|title=ノーベル賞:江崎、小林、朝永氏の銅像やレリーフ設置 完成記念式でお披露目 「子どもが夢を」−−つくば・中央公園 ／茨城 - 毎日新聞|archive-date=April 24, 2015|access-date=August 9, 2019}}</ref>

=== Awards ===
{| class="wikitable"
! Country
! Year
! Institute
! Award
! Citation
! {{Reference column heading}}
|-
|{{Flag|Japan}}
| 1959
| Nishina Memorial Foundation
| [[Nishina Memorial Prize]]
| "Invention of the Esaki diode"
| <ref>{{Cite web|title=Nishina Memorial Prize|url=https://www.nishina-mf.or.jp/project_en/kinen_en/|url-status=live|publisher=Nishina Memorial Foundation|archive-url=https://web.archive.org/web/20250614013645/https://www.nishina-mf.or.jp/project_en/kinen_en/|archive-date=2025-06-14|access-date=2021-04-20}}</ref>
|-
| {{Flag|United States}}
| 1961
| [[Institute of Radio Engineers]]
| [[IRE Morris Liebmann Memorial Prize]]
| "For important contributions to the theory and technology of solid-state devices, particularly as embodied in the tunnel diode"
| <ref>{{Cite web|title=IEEE Morris N. Liebmann Memorial Award Recipients|url=http://www.ieee.org/documents/liebmann_rl.pdf|url-status=dead|publisher=[[IEEE]]|archive-url=https://web.archive.org/web/20160303211541/http://www.ieee.org/documents/liebmann_rl.pdf|archive-date=2016-03-03|access-date=2011-02-27}}</ref>
|-
| {{Flag|United States}}
| 1961
| [[Franklin Institute]]
| [[Stuart Ballantine Medal]]
| "For the development of the tunnel diode and the discovery and utilization of quantum-mechanical tunneling in semiconductors"
| <ref>{{Cite web|title=Leo Esaki|url=https://fi.edu/en/awards/laureates/leo-esaki|url-status=live|publisher=[[Franklin Institute]]|archive-url=https://web.archive.org/web/20240817044441/https://fi.edu/en/awards/laureates/leo-esaki|archive-date=2024-08-17|access-date=2025-10-27}}</ref>
|-
| {{Flag|Sweden}}
| 1973
| [[Royal Swedish Academy of Sciences]]
| [[Nobel Prize in Physics]]
| "For their experimental discoveries regarding tunneling phenomena in semiconductors and superconductors, respectively" (with [[Ivar Giaever]])
| <ref name=NobelFacts/>
|-
| {{Flag|United States}}
| 1985
| [[American Physical Society]]
| [[International Prize for New Materials]]
| "For their conception of artificial semiconductor superlattices and his recognition that such structures have realizable and would have novel electronic properties" (with [[Leroy Chang]] and [[Raphael Tsu]])
| <ref>{{Cite web|title=James C. McGroddy Prize for New Materials |url=http://www.aps.org/programs/honors/prizes/mcgroddy.cfm|website=www.aps.org|access-date=2023-10-08}}</ref>
|-
| {{Flag|United States}}
| 1989
| [[University of Pennsylvania]]
| [[Harold Pender Award]]
| "Pioneer in tunneling phenomena in semiconductors and development of quantum well structures"
| <ref>{{Cite web|title=The Harold Pender Award Lecture |url=https://events.seas.upenn.edu/distinguished-lectures/pender-lecture/|url-status=live|publisher=[[University of Pennsylvania]]|archive-url=https://web.archive.org/web/20250815005242/https://events.seas.upenn.edu/distinguished-lectures/pender-lecture/|archive-date=2025-08-15|access-date=2024-09-19}}</ref>
|-
| {{Flag|United States}}
|1991
| [[IEEE]]
| [[IEEE Medal of Honor]]
| "For contributions to and leadership in tunneling, semiconductor superlattices, and quantum wells"
| <ref>{{Cite web|title=Leo Esaki|url=https://corporate-awards.ieee.org/recipient/leo-esaki/|url-status=live|publisher=[[IEEE]]|archive-url=https://web.archive.org/web/20230926124133/https://corporate-awards.ieee.org/recipient/leo-esaki/|archive-date=2023-09-26|access-date=2024-05-13}}</ref>
|-
| {{Flag|Japan}}
| 1998
| Japan Prize Foundation
| [[Japan Prize]]
| "For the creation and realization of the concept of man-made superlattice crystals which led to generation of new materials with useful applications"
| <ref name=jp/>
|}

=== Memberships ===
{| class="wikitable"
! Country
! Year
! Institute
! Type
! Section
! {{Reference column heading}}
|-
| {{Flag|United States}}
| 1976
| [[National Academy of Sciences]]
| International Member
| Engineering Sciences
| <ref>{{Cite web|title=Leo Esaki|url=https://www.nasonline.org/directory-entry/leo-esaki-axpoif/|url-status=live|publisher=[[National Academy of Sciences]]|archive-url=https://web.archive.org/web/20250813104325/https://www.nasonline.org/directory-entry/leo-esaki-axpoif/|archive-date=2025-08-13|access-date=2025-10-27}}</ref>
|-
| {{Flag|United States}}
| 1977
| [[National Academy of Engineering]]
| International Member
| Electronics, Communication & Information Systems
| <ref>{{Cite web|title=Dr. Leo Esaki|url=https://www.nae.edu/28169/Dr-Leo-Esaki|publisher=[[National Academy of Engineering]]|access-date=2025-10-27}}</ref>
|-
| {{Flag|United States}}
| 1991
| [[American Philosophical Society]]
| Member
| Mathematical and Physical Sciences
| <ref>{{Cite web|title=Member History |url=https://search.amphilsoc.org/memhist/search?creator=Leo+Esaki&title=&subject=&subdiv=&mem=&year=&year-max=&dead=&keyword=&smode=advanced|publisher=[[American Philosophical Society]]|access-date=2025-11-01}}</ref>
|}

=== Honorary degrees ===
{| class="wikitable"
! Territory
! Year
! Institute
! Degree
! {{Reference column heading}}
|-
| {{Flag|Hong Kong}}
| 2001
| [[HKUST]]
| [[Doctor of Science]]
| <ref>{{Cite web|title=Honorary Doctorates|url=https://ccss.hkust.edu.hk/honorary-doctorates|publisher=[[HKUST]]|access-date=2025-11-01}}</ref>
|}

== Family ==
Esaki's daughter, Anna Esaki, is married to [[Craig S. Smith]], former [[Shanghai]] bureau chief of ''[[The New York Times]]'' and [[China]] bureau chief of ''[[The Wall Street Journal]]''.<ref>{{Cite news|date=January 14, 1990|title=Anna Esaki Wed To Craig S. Smith|language=en-US|work=The New York Times|url=https://www.nytimes.com/1990/01/14/style/anna-esaki-wed-to-craig-s-smith.html|access-date=August 19, 2021|issn=0362-4331}}</ref>

== See also ==
* [[List of Japanese Nobel laureates]]
* [[List of Nobel laureates affiliated with the University of Tokyo]]

== References ==
{{Reflist}}

== Further reading ==
*Large scale integrated circuits technology: state of the art and prospects, ''proceedings of the NATO Advanced Study Institute on "Large Scale Integrated Circuits Technology: State of the Art and Prospects," Erice, Italy, July 15–27, 1981 ''/ edited by Leo Esaki and Giovanni Soncini (1982)
*''Highlights in condensed matter physics and future prospects'' / edited by Leo Esaki (1991)

== External links ==
{{Commons category-inline}}
* {{Nobelprize}} including the Nobel Lecture, December 12, 1973 ''Long Journey into Tunnelling''
* [https://web.archive.org/web/20050117192748/http://www-03.ibm.com/ibm/history/history/year_1973.html IBM record]
* IEEE History Center – Leo Esaki. Retrieved July 19, 2011 from [http://www.ieeeghn.org/wiki/index.php/Leo_Esaki Leo Esaki - Engineering and Technology History Wiki]
* Sony History – The Esaki Diode.  Retrieved August 5, 2003 from [https://web.archive.org/web/20030804052243/http://www.sony.net/Fun/SH/1-7/h5.html Sony Global | Sony History]
*[http://www.vega.org.uk/video/programme/28 Freeview video 'An Interview with Leo Esaki' by the Vega Science Trust]

{{IEEE Medal of Honor 1976-2000}}
{{Japan Prize}}
{{Nobel Prize in Physics Laureates 1951-1975}}
{{1973 Nobel Prize winners}}
{{Japanese Nobel laureates}}

{{Authority control}}

{{DEFAULTSORT:Esaki, Leo}}
[[Category:1925 births]]
[[Category:Living people]]
[[Category:Foreign associates of the National Academy of Sciences]]
[[Category:Foreign members of the Russian Academy of Sciences]]
[[Category:Fellows of the American Physical Society]]
[[Category:IBM Fellows]]
[[Category:IEEE Medal of Honor recipients]]
[[Category:Japanese Nobel laureates]]
[[Category:20th-century Japanese physicists]]
[[Category:Japanese nanotechnologists]]
[[Category:20th-century Japanese inventors]]
[[Category:Academic staff of Kwansei Gakuin University]]
[[Category:Academic staff of Kyoto University]]
[[Category:Nobel laureates in Physics]]
[[Category:People from Higashiōsaka]]
[[Category:Scientists from Osaka Prefecture]]
[[Category:Semiconductor physicists]]
[[Category:Recipients of the Order of Culture]]
[[Category:Grand Cordons of the Order of the Rising Sun]]
[[Category:Academic staff of the University of Tsukuba]]
[[Category:Foreign associates of the National Academy of Engineering]]
[[Category:University of Tokyo alumni]]
[[Category:International members of the American Philosophical Society]]
[[Category:Japanese men centenarians]]