I need to generate following notation in LaTeX.
It's used in differential geometry to denote vector fields.
I can't find documentation and detexify is not helpful either.

I need to generate following notation in LaTeX.
It's used in differential geometry to denote vector fields.
I can't find documentation and detexify is not helpful either.

(As Werner pointed out before me) It's in the MnSymbol package as \vertbowtie. And as Torbjorn T. pointed out, one does not, in general, want to get all the MnSymbols loaded, as they overwrite a lot of default stuff. Using the pointer that Torbjorn provided (Importing single symbol from MnSymbol), I was able to look at MnSymbol.dtx on CTAN (http://mirrors.ctan.org/fonts/mnsymbol/tex/MnSymbol.dtx) to find that \vertbowtie was defined as
\Decl@Mn@Char\vertbowtie {MnSyC}{\mathbin}
I was also able to use the fonttable package to display the MnSymbolC font table to determine that the \vertbowtie was symbol 39. And armed with that information, I was able to extract just that symbol as follows:
\documentclass{article}
\DeclareFontFamily{U} {MnSymbolC}{}
\DeclareFontShape{U}{MnSymbolC}{m}{n}{
<-6> MnSymbolC5
<6-7> MnSymbolC6
<7-8> MnSymbolC7
<8-9> MnSymbolC8
<9-10> MnSymbolC9
<10-12> MnSymbolC10
<12-> MnSymbolC12}{}
\DeclareFontShape{U}{MnSymbolC}{b}{n}{
<-6> MnSymbolC-Bold5
<6-7> MnSymbolC-Bold6
<7-8> MnSymbolC-Bold7
<8-9> MnSymbolC-Bold8
<9-10> MnSymbolC-Bold9
<10-12> MnSymbolC-Bold10
<12-> MnSymbolC-Bold12}{}
\DeclareSymbolFont{MnSyC} {U} {MnSymbolC}{m}{n}
%\Decl@Mn@Char\vertbowtie {MnSyC}{\mathbin}
\DeclareMathSymbol{\vertbowtie}{\mathbin}{MnSyC}{39}
%\usepackage{fonttable}
\begin{document}
%\fonttable{MnSymbolC10}
$a \vertbowtie b$
\end{document}

For those of us who don't breathe LaTeX fonts, several points were necessary for me to grok, that were not made clear at Importing single symbol from MnSymbol.
1) The \DeclareSymbolFont macro had to come before the \DeclareMathSymbol, so that the name MnSyC was recognized.
2) The name \mathbin in the \DeclareMathSymbol macro must match the last argument of \Decl@Mn@Char, as found in the font's sty/dtx file.
3) The macro \Decl@Mn@Char is not part of the solution, but rather one must find it in the dtx file in order to obtain the font family (MnSyC) and the "category" (\mathbin). [sorry for the use of imprecise terminology...I'm sure these things have official names].
Of course, no Segletes solution would be complete without an alternate stackengine solution:
\documentclass{article}
\usepackage{stackengine}
\def\myvertbowtie{\mathrel{\stackon[0pt]{\def\stacktype{L}%
\stackon[0pt]{\sffamily x}{\rule{1ex}{.1ex}}}{\rule{1ex}{.1ex}}}}
\parskip 1em
\begin{document}
\( a \myvertbowtie b \)
\end{document}

MnSymbolprovides\vertbowtie... – Werner Sep 09 '13 at 18:24\newcommand{\vectfield}{\mathrel{\text{\scalebox{0.85}{\rotatebox[origin=c]{90}{$\vartriangleright\mkern-4mu\vartriangleleft$}}}}}. Requiresgraphicx,amsmathandamssymb. Adjust 0.85 to your needs. – karlkoeller Sep 09 '13 at 19:09