Field-enhanced magnetic moment in ellipsoidal nano-hematite
Bulk hematite is a canted antiferromagnet at room temperature and displays weak magnetic coercivity above the Morin transition temperature T _M ∼ 262 K. Below T _M , hematite displays traditional antiferromagnetic behavior, with no net magnetic moment or magnetic hysteresis. Here, we report that el...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2014-01-01
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| Series: | Materials Research Express |
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| Online Access: | https://doi.org/10.1088/2053-1591/1/2/026114 |
| _version_ | 1827869694467506176 |
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| author | Vikash Malik Somaditya Sen David R Gelting Marija Gajdardziska-Josifovska Marius Schmidt Prasenjit Guptasarma |
| author_facet | Vikash Malik Somaditya Sen David R Gelting Marija Gajdardziska-Josifovska Marius Schmidt Prasenjit Guptasarma |
| author_sort | Vikash Malik |
| collection | DOAJ |
| description | Bulk hematite is a canted antiferromagnet at room temperature and displays weak magnetic coercivity above the Morin transition temperature T _M ∼ 262 K. Below T _M , hematite displays traditional antiferromagnetic behavior, with no net magnetic moment or magnetic hysteresis. Here, we report that ellipsoidal nanocrystals of hematite (ENH) display a significant field-enhanced magnetic moment (FEMM) upon being poled by a magnetic field. This poled moment displays a giant coercive field of nearly 6000 Oe at low temperature. Atomic resolution transmission electron microscopy indicates that the nanocrystals are single crystalline, and that the surfaces are bulk-terminated. The apical terminations include the <001> sets of planes, which are implicated in possible formation of FM-arrangements near the surface. We tentatively suggest that FEMM in ENH could also arise from uncompensated surface spins or a shell of ordered spins oriented and pinned near the surface by a magnetic field. The gradual loss of magnetic moment with increasing temperature could arise as a result of competition between surface pinning energy, and kT. The large coercive field points toward possible applications for ENH in digital magnetic recording. |
| first_indexed | 2024-03-12T15:47:45Z |
| format | Article |
| id | doaj.art-3d3f7c5f7ccd4cf88e590faea2f55be6 |
| institution | Directory Open Access Journal |
| issn | 2053-1591 |
| language | English |
| last_indexed | 2024-03-12T15:47:45Z |
| publishDate | 2014-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | Materials Research Express |
| spelling | doaj.art-3d3f7c5f7ccd4cf88e590faea2f55be62023-08-09T15:20:09ZengIOP PublishingMaterials Research Express2053-15912014-01-011202611410.1088/2053-1591/1/2/026114Field-enhanced magnetic moment in ellipsoidal nano-hematiteVikash Malik0Somaditya Sen1David R Gelting2Marija Gajdardziska-Josifovska3Marius Schmidt4Prasenjit Guptasarma5Physics Department, University of Wisconsin Milwaukee , 1900 E. Kenwood Blvd Milwaukee-WI 53211, USAPhysics Department, University of Wisconsin Milwaukee , 1900 E. Kenwood Blvd Milwaukee-WI 53211, USAPhysics Department, University of Wisconsin Milwaukee , 1900 E. Kenwood Blvd Milwaukee-WI 53211, USAPhysics Department, University of Wisconsin Milwaukee , 1900 E. Kenwood Blvd Milwaukee-WI 53211, USAPhysics Department, University of Wisconsin Milwaukee , 1900 E. Kenwood Blvd Milwaukee-WI 53211, USAPhysics Department, University of Wisconsin Milwaukee , 1900 E. Kenwood Blvd Milwaukee-WI 53211, USABulk hematite is a canted antiferromagnet at room temperature and displays weak magnetic coercivity above the Morin transition temperature T _M ∼ 262 K. Below T _M , hematite displays traditional antiferromagnetic behavior, with no net magnetic moment or magnetic hysteresis. Here, we report that ellipsoidal nanocrystals of hematite (ENH) display a significant field-enhanced magnetic moment (FEMM) upon being poled by a magnetic field. This poled moment displays a giant coercive field of nearly 6000 Oe at low temperature. Atomic resolution transmission electron microscopy indicates that the nanocrystals are single crystalline, and that the surfaces are bulk-terminated. The apical terminations include the <001> sets of planes, which are implicated in possible formation of FM-arrangements near the surface. We tentatively suggest that FEMM in ENH could also arise from uncompensated surface spins or a shell of ordered spins oriented and pinned near the surface by a magnetic field. The gradual loss of magnetic moment with increasing temperature could arise as a result of competition between surface pinning energy, and kT. The large coercive field points toward possible applications for ENH in digital magnetic recording.https://doi.org/10.1088/2053-1591/1/2/026114magnetismnanocrystalshematititecoercive fieldcore-shell nanocrystalssurface pinning |
| spellingShingle | Vikash Malik Somaditya Sen David R Gelting Marija Gajdardziska-Josifovska Marius Schmidt Prasenjit Guptasarma Field-enhanced magnetic moment in ellipsoidal nano-hematite Materials Research Express magnetism nanocrystals hematitite coercive field core-shell nanocrystals surface pinning |
| title | Field-enhanced magnetic moment in ellipsoidal nano-hematite |
| title_full | Field-enhanced magnetic moment in ellipsoidal nano-hematite |
| title_fullStr | Field-enhanced magnetic moment in ellipsoidal nano-hematite |
| title_full_unstemmed | Field-enhanced magnetic moment in ellipsoidal nano-hematite |
| title_short | Field-enhanced magnetic moment in ellipsoidal nano-hematite |
| title_sort | field enhanced magnetic moment in ellipsoidal nano hematite |
| topic | magnetism nanocrystals hematitite coercive field core-shell nanocrystals surface pinning |
| url | https://doi.org/10.1088/2053-1591/1/2/026114 |
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