Antiferromagneticresonancestudyofsodaliteloadedwithsodium by multi-frequencyESR

摘要

We havecarriedoutelectronspinresonance(ESR)measurementsonpowdersamplesofsodaliteloaded with Naatseveralfrequenciesbetween9.7and35GHzandattemperaturesbetween1.5and60K.The ESR absorptionspectrumbelowaNe′ el temperature TN turns intoanasymmetricspectrumwithalong tail atlowfieldsfromasymmetriconeabove TN. Thelineshapeofthespectrabelow TN is analyzedbya powder patternsimulationoftheantiferromagneticresonancespectrawitheasy-planeanisotropy.The calculatedlineshapereproducestheexperimentaloneconsiderablywellbyassumingaGaussian distributionofthezero-fieldenergygap.Wehaveevaluatedasmallanisotropyfieldofabout2104 T by usingtheexchangecouplingconstantcalculatedfromtheWeissandtheNe′ el temperatures.This result indicatesthatthesodaliteloadedwithNaisquiteanidealHeisenbergantiferromagnetas expectedfromthes-electroncharacterofNaclustersandthecubicarrangementofnano-spacesinthe sodalite.