CCNUMBER 31ThisWeeksCitationClassic________ [606885]

CC/NUMBER 31ThisWeek’sCitationClassic________
f’N~eIL.Propri~t~s magn~tiques desferrites:ferrima~n8tisme et
antiferromagn~tisme. (Magnetic properties offemtes:ferrimagnetism and
antiferromagnetism.) Ann.Phys.Paris3:137-98, 1948.
(Facult~desSciences. Univ.Grenoble, France) –
Thisreportintroduced andstudiedanewcategory
ofmagnetic substances, ferrimagnets, whichare
addedtothosealreadyknown:thediamagnets,
paramagnets, andferromagnets. Ferrimagnetism
playsanimportant partinindustrial applications.
[TheSCI~indicates thatthispaperhasbeencited
inover595publications since1955,makingitthe
most-cited papereverpublished inthisjournal.]
February 24,1984
“Since1947,themagnetic properties ofspinet
ferrites(thegeneralformulaFe2O3MO, whereMis
abivalentmetal)haveremained completely unex-
plained.Thearticleinquestion, whichwasaccept.
edwithonlyabitofreticence bytheeditorial
committee oftheAnnaiesdePhysique, givesa
complete andquantitative interpretation ofthese
properties, basedonalargenumberofoutsidees.
perimental results,Itshowsthatthereexistsanew
category ofmagnetism: ferrimagnetism. Incla5si.
calferromagnets, likeironornickel,theinterac-
tionsbetween atomicmagnetic moments tendto
alignthemselves paralleltoeachotherinthesame
sense;thatis,atlowtemperature allthese
moments becomeparallel.Onthecontrary, infer-
rimagnets, themagnetic atomsaresharedbetween
twodistinctAcrystalline andBcrystalline sub-
lattices. Atlowtemperature, themacroscopic
spontaneous attraction Isequaltothedifference
ofspontaneous attraction oftheIwosub-lattices.
“Anfiferromagnetism, ofwhichIpredicted the
existence asearlyas1932,1,2beforethediscoveryin1938~ofbodiespossessing suchproperties, isa
particular caseofferrimagnetism wherethetwo
sub-lattices sireidentical, withequalspontaneous
magnetizations, andopposedtoalltemperatures.
“Myworkof1948predicted theexistence of
substances ofwhichthespontaneous attraction
presents veryunusualabnormal thermalvaria-
tions.Alltheseanomalies wereultimately re-
trievedexperimentally, as,forexample, those
wherethespontaneous magnetization counter-
balance,Inasense,Isatacertaincompensation
temperature. Atthistemperature, thespontaneous
Amagnetizations andBmagnetizations areequal
andopposed toeachother.Lithium-chrome fer-
rite4-~aswellassomegarnets7areexamples of
this.
“In1954,°’~thetheoryofferrimagnetism con-
tributedagreatdealtothediscovery ofanewand
veryrichfamilyofferrimagnetic substances: the
rareearthgarnetferrites7oftheformFe5T3O12,
whereTisarareearthandwhereatrivalentele-
mentcanbesubstituted forFe.Manysamples
fromthisfamilyhavefoundinteresting applica-
tions,suchasyttriumgarnets.
“Since1948,thousands ofpublications have
beenwrittenonthesubjectofferrimagnetism and
onecanalsosaythattheirmagnetic properties are
betterunderstood thanthose01metallicferromag.
nets.Considering thegreatinterestinferrimagne.
tismforbasicphysicsandtheknowledge ofthe
different typesofmagnetic interactions, theim-
portance andthevarietyofapplications arecon-
siderable. Manyofthesebodiesareinsulators, and
evenexcellent electrical insulators, suchasgar-
nets.Theycanthusbeusedinveryhighfrequency
methods, suchasInradar.Theseapplications are
facilitated bythepossibility ofpreparing themin
largemonocryatals.
“Forthisdiscovery, IwontheNobelprizein
1970,aswellasotherdistinctions.”
I.N8eIL.Influesce desfluctustions duchampmolEculsire surletpropri8t8s magnftiques descorps.
Ann.Phyt.Pan,18:5-105, 1932.
2.N4e1L.Theoryofconstantparsmsgnetism. Application tomsnganese. CRAcad.Sci.Paris203:304-6, 1936.
3.BIzetieH,SquireCF&TialB.Transition pointofmagnetic susceptibility ofMsO.
CRAcad.Sci.Pans207:449-50, 1938.
4.Gorse,EW.Saturation magnetization andcrystalchemistry offerrtmsgnetic oxides.
PhillpjRet.Rep.9:295-320, 1954.(Cited250timessince1955.)
5.— -Saturation msgnetization andcrystalchemistry offemmagnetic oxides.2.Theoryofferrimsgnetism.
PhilipsRet.Rep.9:321-65, 1954.(Cited100timessince1955.)
6. —.– -Saturation magnetization andcrystalchemistry offenitnagnetic oxides.3.Saturation moment and
physicalchemistry offerrimagnetic spinelscontaining titanium. PhilipsRe,.Rep.9:403-43. l954.
(Cited135timessince1955.)
7.NEalL,Pautbenet R&Dreylas B.Therareearthgarnets. Prog.LowTemp.Phys.4:344-83, 1964.
8.P.utbenet R&BlumP.Thermoniagnetic studyofgadolinium ferrite.CRAcad.Sri.Paris239:33-5, 1954.
9.NEalL.Theinterpretation ofthemagnetic properties oftherareearthferntes.CRAcad.Sri.Pan,239:8-11. 1954.LouisN~eI
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