Max-Planck-Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, D-01187 Dresden, Germany.
Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22603 Hamburg, Germany.
Nat Commun. 2014 Dec 23;5:5731. doi: 10.1038/ncomms6731.
The magnetic excitations in the cuprate superconductors might be essential for an understanding of high-temperature superconductivity. In these cuprate superconductors the magnetic excitation spectrum resembles an hour-glass and certain resonant magnetic excitations within are believed to be connected to the pairing mechanism, which is corroborated by the observation of a universal linear scaling of superconducting gap and magnetic resonance energy. So far, charge stripes are widely believed to be involved in the physics of hour-glass spectra. Here we study an isostructural cobaltate that also exhibits an hour-glass magnetic spectrum. Instead of the expected charge stripe order we observe nano phase separation and unravel a microscopically split origin of hour-glass spectra on the nano scale pointing to a connection between the magnetic resonance peak and the spin gap originating in islands of the antiferromagnetic parent insulator. Our findings open new ways to theories of magnetic excitations and superconductivity in cuprate superconductors.
在高温超导体中，铜酸盐超导体中的磁激发可能对其超导机制的理解至关重要。在这些铜酸盐超导体中，磁激发谱类似于沙漏形，并且某些共振磁激发被认为与配对机制有关，这一点得到了超导能隙和磁共振能量普遍线性标度的观察结果的支持。到目前为止，电荷条纹被广泛认为与沙漏谱的物理性质有关。在这里，我们研究了一种具有相同结构的钴酸盐，它也表现出沙漏状的磁谱。我们没有观察到预期的电荷条纹有序，而是观察到纳米相分离，并揭示了在纳米尺度上沙漏谱微观分裂的起源，这表明磁共振峰与源自反铁磁母体绝缘体能隙的自旋隙之间存在联系。我们的发现为铜酸盐超导体中磁激发和超导的理论开辟了新的途径。
