Bonding, moment formation, and magnetic interactions inCa14MnBi11and

Abstract

The "14-1-11" phase compounds based on magnetic Mn ions and typified by Ca14MnBi11 and Ba14MnBi11 show unusual magnetic behavior, but the large number (104) of atoms in the primitive cell has precluded any previous full electronic structure study. Using an efficient, local orbital based method within the local spin density approximation to study the electronic structure, we find a gap between a bonding valence band complex and an antibonding conduction band continuum. The bonding bands lack one electron per formula unit of being filled, making them low carrier density p-type metals. The hole resides in the MnBi4 tetrahedral unit and partially compensates the high spin d 5 Mn moment, leaving a net spin near 4 µB that is consistent with experiment. These manganites are composed of two disjoint but interpenetrating 'jungle gym' networks of spin 4 2 MnBi49− units with ferromagnetic interactions within the same network, and weaker couplings between the networks whose sign and magnitude is sensitive to materials parameters. Ca14MnBi11 is calculated to be ferromagnetic as observed, while for Ba14MnBi11 (which is antiferromagnetic) the ferroand antiferromagnetic states are calculated to be essentially degenerate. The band structure of the ferromagnetic states is very close to half metallic. 71.20.Be,71.15.Mb

Kondo lattice behavior in the ordered dilute magnetic semiconductorYb14−xLaxMnSb11

“…[9] A d 5 +hole (d 5 +h) picture is also expected from detailed electronic structure calculations on related Ca 14 MnBi 11 compound. [10] This is in accord with the understanding of the most heavily studied dilute magnetic semiconductor (DMS) GaAs:Mn which is suggested by multiple experiments to have also a d 5 +h Mn configuration. [2,3,11] We grew relatively large (up to 0.5 g) single crystals of Yb 14 MnSb 11 with and without various dopants (La, Te, Y, Sc etc.)…”

“…The Fermi energy, E F , from the free electron model is given by h 2 k 2 F /(4π 2 m e ) which gives E F = 0.5 eV. If the band mass, m b ≈ 1.8m e , is used (as measured from optical data [12] or estimated from electronic structure calculations, [10] or estimated [17] from the room temperature Seebeck coefficient of +44 µV/K) E F ∼ 0.28 eV. The measured values for the carrier concentration indicate a substantial mass enhancement for the carriers of about 15m e for the undoped crystal and 11m e for the La doped crystal.…”

Complex Magnetic Ordering in Eu3InP3: A New Rare Earth Metal Zintl Compound

“…[6][7][8][9][10][11][12][13] In addition, superconductivity has been discovered in several Zintl compounds. 5,13-15 Because of their unique magnetoresistive properties, [16][17][18][19][20][21][22] we have been exploring a flux synthesis * Author to whom correspondence should be addressed. E-mail: smkauzlarich@ucdavis.edu.…”

Different origins of the ferromagnetic order in (Ga,Mn)As and (Ga,Mn)N

“…It uses a very efficient localized atomic orbital basis set [24,25,26] and norm conserving pseudopotentials in the separate Kleinman-Bylander form [27]. It is therefore ideal to simulate arrangements of hundreds and even thousands of atoms, hence DMS with low Mn concentrations [14] and related systems [28].…”