jap banner
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

SECTION LISTING

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

15 May 2003

Volume 93, Issue 10, pp. 5855-8792

Return to All Sections
back to top
RSS Feeds

Atomic clusters of magnetic oxides: Structure and phonons

A. Kirilyuk, K. Demyk, G. von Helden, G. Meijer, A. I. Poteryaev, and A. I. Lichtenstein

J. Appl. Phys. 93, 7379 (2003); http://dx.doi.org/10.1063/1.1558252 (3 pages) | Cited 3 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This work represents a combined experimental and theoretical study of structural and magnetic properties of clusters made of cobalt, chromium, and manganese oxides. The clusters were prepared in a molecular cluster source by oxidation of laser-vaporized metal and studied in a time-of-flight spectrometer. Infrared laser-induced cluster dissociation experiments revealed the spectrum of cluster vibrational states. We also performed ab initio local spin density approximation calculations of the equilibrium geometry, electronic structure, and magnetic properties of these clusters. © 2003 American Institute of Physics.
Show PACS
61.46.-w Structure of nanoscale materials
63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
75.50.Tt Fine-particle systems; nanocrystalline materials
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
73.22.Dj Single particle states
36.40.Cg Electronic and magnetic properties of clusters
36.40.Mr Spectroscopy and geometrical structure of clusters

Temperature dependence of magnetic resonance in NiO nanoparticles

V. V. Pishko, S. L. Gnatchenko, V. V. Tsapenko, R. H. Kodama, and Salah A. Makhlouf

J. Appl. Phys. 93, 7382 (2003); http://dx.doi.org/10.1063/1.1558253 (3 pages) | Cited 10 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Magnetic resonance measurements of different size NiO nanoparticles were performed at frequencies below 33 cm−1 and in the temperature range 300–500 K. The samples were earlier investigated by superconducting quantum interference device magnetometry and electron spin resonance spectrometry. The spectra were scanned by changing the sample temperature at fixed frequencies. At room temperature, resonance frequency for bulk NiO is 36.5 cm−1. At higher temperatures, the magnetic resonance frequency becomes lower, and at the Néel temperature goes to zero. For the 435 Å nanoparticles, we detected only one resonance peak. Extrapolation of the dependence to zero frequency gives a Néel temperature of 492 K. For 57 Å NiO, we observed two different peaks. One of them was at the same place as for 435 Å NiO, and another one was at higher temperatures. There exists several mechanisms which determine the magnetic structure of NiO nanoparticles, and, respectively, its resonance spectra. We believe that the magnetic resonance in 435 Å NiO corresponds to a bulklike structure, and the detection of two separate peaks in 57 Å NiO by a “size effect,” which is consistent with a many-sublattice magnetic structure and corresponding additional exchange modes of magnetic resonance. © 2003 American Institute of Physics.
Show PACS
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance
75.50.Tt Fine-particle systems; nanocrystalline materials
75.50.Ee Antiferromagnetics
61.46.-w Structure of nanoscale materials
81.07.Wx Nanopowders
75.25.-j Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.)
75.30.Et Exchange and superexchange interactions

Nanoparticle surface charge density in ionic magnetic fluids: The effect of particle–particle interaction

Qu Fanyao and P. C. Morais

J. Appl. Phys. 93, 7385 (2003); http://dx.doi.org/10.1063/1.1544493 (3 pages) | Cited 1 time

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this study, particle–particle interaction in ionic magnetic fluids is systematically investigated by self-consistently solving the coupled Schrödinger and Poisson equations. It was found that particle–particle interaction changes the colloid characteristics by changing the energy level position E and the nanoparticle surface charge density σ. Formation of bonding and antibonding states due to particle–particle interaction in a two-particle system (dimer) was studied as a function of particle diameter, particle–particle distance, and band offset. The coupling strength within the dimer is characterized by a systematic dependence of both the bonding and antibonding levels and surface charge density upon particle diameter, particle–particle distance, and band offset values. The quantum-model picture discussed in the article opens up new insights into the physics of coupled colloidal particles. © 2003 American Institute of Physics.
Show PACS
75.50.Mm Magnetic liquids
75.50.Tt Fine-particle systems; nanocrystalline materials
61.46.-w Structure of nanoscale materials
81.07.Wx Nanopowders
82.70.Dd Colloids
75.40.Mg Numerical simulation studies

e2/h quantization of the conduction in Cu nanowires

D. M. Gillingham, I. Linington, C. Müller, and J. A. C. Bland

J. Appl. Phys. 93, 7388 (2003); http://dx.doi.org/10.1063/1.1544494 (2 pages) | Cited 12 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated the quantum transport behavior of Cu nanowires created by bringing two macroscopic Cu wires into and out of contact at room temperature. We have observed quantum conductance with steps of both e2/h and 2e2/h. We conclude that the spin degeneracy can be broken in nonmagnetic Cu nanowires. © 2003 American Institute of Physics.
Show PACS
73.63.Nm Quantum wires
73.21.Hb Quantum wires
73.23.-b Electronic transport in mesoscopic systems
72.25.Ba Spin polarized transport in metals
72.15.Eb Electrical and thermal conduction in crystalline metals and alloys

Spin waves in random spin chains

Xin Wan, Kun Yang, Chenggang Zhou, and R. N. Bhatt

J. Appl. Phys. 93, 7390 (2003); http://dx.doi.org/10.1063/1.1541640 (3 pages)

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We study quantum spin-1/2 Heisenberg ferromagnetic chains with dilute random antiferromagnetic impurity bonds with the modified spin-wave theory. By describing thermal excitations in the language of spin waves, we observe a low-temperature Curie susceptibility due to the formation of large spin clusters first predicted by the real-space renormalization-group approach, as well as a crossover to a pure ferromagnetic spin-chain behavior at intermediate and high temperatures. We compare our results of the modified spin-wave theory to quantum Monte Carlo simulations. © 2003 American Institute of Physics.
Show PACS
75.10.Jm Quantized spin models, including quantum spin frustration
75.30.Ds Spin waves
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
75.40.Mg Numerical simulation studies
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close