### Session G2: Quantum Criticality in Cuprates

8:00 AM–11:00 AM, Tuesday, March 14, 2006
Baltimore Convention Center Room: Ballroom III

Chair: Lia Krusin-Elbaum, IBM

Abstract ID: BAPS.2006.MAR.G2.4

### Abstract: G2.00004 : Field-induced magnetism in a high-temperature superconductor

9:48 AM–10:24 AM

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#### Author:

Bella Lake
(Hahn-Meitner Institut, Berlin)

Many physical properties of the high-temperature (high-$T_{c}$) superconductors are two-dimensional phenomena derived from their square planar CuO$_{2}$ building blocks. This is especially true of the magnetism from the copper ions electronically connected to each other via the $p$-orbitals of intervening oxygen atoms. As mobile charge carriers enter these CuO$_{2}$ layers, the antiferromagnetism of the parent insulators, where each copper spin is antiparallel to its nearest neighbours, evolves into a fluctuating state where the spins show tendencies towards magnetic order of a longer periodicity. For certain charge carrier densities, the quantum fluctuations are sufficiently suppressed to yield static long-period order and external magnetic fields also induce such order. Here we show, using neutron scattering measurements, that in contrast to the chemically-controlled order in superconducting La$_{2-x}$Sr$_{x}$CuO$_{4}$, the field-induced order is actually three-dimensional, implying significant magnetic linkage between the CuO$_{2}$ planes. The results are important because they reveal the presence of three-dimensional magnetic couplings which survive into the superconducting state, and coexist with the crucial inter-layer couplings responsible for the three-dimensional superconductivity.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2006.MAR.G2.4