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UID:DSC-17594
DTSTART;TZID=Europe/Berlin:20201124T145000
SEQUENCE:1606173021
TRANSP:OPAQUE
DTEND;TZID=Europe/Berlin:20201124T162000
URL:https://www.dresden-science-calendar.de/calendar/en/detail/17594
LOCATION:TUD\,    
SUMMARY:Kulbakov: Destruction of long-range magnetic order in Cu2GaBO5  and
  Cu2AlBO5 ludwigites by an external magnetic field
CLASS:PUBLIC
DESCRIPTION:Speaker: Anton Kulbakov\nInstitute of Speaker: Technische Unive
 rsität Dresden\nTopics:\nPhysik\n Location:\n  Name: TUD (C213)\n  Street
 :   \n  City:  \n  Phone: \n  Fax: \nDescription: <p>Abstract: The quantum
  spin systems M22+M′BO5 (M′ = Al\, Ga) with the ludwigite crystal<br /
 > structure consist of a structurally ordered Cu2+ sublattice in the form 
 of three-leg<br /> ladders\, interpenetrated by a structurally disordered 
 sublattice with statistically<br /> random site occupation by magnetic Cu2
 + and nonmagnetic Ga3+ or Al3+ ions. A<br /> microscopic analysis based on
  density-functional-theory calculations for<br /> Cu2GaBO5 reveals a frust
 rated quasi-two-dimensional spin model featuring five<br /> inequivalent a
 ntiferromagnetic exchanges. A broad low-temperature 11B nuclear<br /> magn
 etic resonance points to a considerable spin disorder in the system. In ze
 ro<br /> magnetic field\, antiferromagnetic order sets in below TN ≈ 4.1
  and ∼2.4 K for the<br /> Ga and Al compounds\, respectively. From neutr
 on diffraction\, we find that the<br /> magnetic propagation vector in Cu2
 GaBO5 is commensurate and lies on the Brillouin-<br /> zone boundary in th
 e (H0L) plane\, qm = (0.45\,0\,−0.7)\, corresponding to a<br /> complex 
 noncollinear long-range ordered structure with a large magnetic unit<br />
  cell. Muon spin relaxation is monotonic\, consisting of a fast static com
 ponent typical<br /> for complex noncollinear spin systems and a slow dyna
 mic component originating<br /> from the relaxation of low-energy spin flu
 ctuations. Gapless spin dynamics<br /> in the form of a diffuse quasielast
 ic peak is also evidenced by inelastic neutron<br /> scattering. Most rema
 rkably\, application of a magnetic field above 1 T destroys<br /> the stat
 ic long-range order\, which is manifested in the gradual broadening<br /> 
 of the magnetic Bragg peaks. We argue that such a crossover from a magneti
 cally<br /> long-range ordered state to a spin-glass regime may result fro
 m orphan spins<br /> on the structurally disordered magnetic sublattice\, 
 which are polarized in magnetic<br /> field and thus act as a tuning knob 
 for field-controlled magnetic disorder.</p>  <p>Host: D. Inosov</p>  <p>RE
 C/C213 (audience capacity: 11)</p>  <p>BigBlueButton: https://selfservice.
 zih.tu-dresden.de/l/link.php?meeting_id=50290&amp\;pin=b4c96a14 (https://s
 elfservice.zih.tu-dresden.de/l/link.php?meeting_id=50290&amp\;pin=b4c96a14
 ) (TUD)</p>  <p>BigBlueButton: https://selfservice.zih.tu-dresden.de/link.
 php?meeting_id=50290&amp\;pin=5c404041 (https://selfservice.zih.tu-dresden
 .de/link.php?meeting_id=50290&amp\;pin=5c404041) (external)</p>
DTSTAMP:20260712T032640Z
CREATED:20201118T230631Z
LAST-MODIFIED:20201123T231021Z
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